This Nokia Series 40 (s40) phone I bought about a month ago has proved my intuitions right in buying it. Its not that I didn't do any research prior to investing 12Gs (grands), but the stuff one can only feel after exploring & exploiting the device to one's own will & whim.. is an incredible sign of awesomeness. (yeah!! the word you're looking for is “whacky articulation”)
[Series 40 is an operating system made by Nokia. Its an embedded software platform, Java based. Series 60 is multitasking Symbian based thing]

So I had this Java(TM) Nokia 3120 earlier and migration to my new Phone has been a piece of cake for most of the thing (moving contacts to SIM card from N3120 & then moving to N5610.. 250 at a time for like 4-5 times & then they show up like nikunjla1, nikunjla2... nikunjla5. Holy Crap!!) except the calendar (you have to manually feed the birthday reminders or any morning gonna be your last!! Lol I still have to input 'em for the first 9months. [seriously, no pun.. or punch.. INTENDED here!]).

Uses internal phone memory of 30MB.

Camera.
Nokia 5610 is one of the best shooters among the series 40 devices.
3.2 megapixel Camera has a variety of modes.
-Video
-Portrait Mode
-Night Mode (works when flash is off)
-Dual-two-LED-Flash (on : off : automatic)
-self-timer (Now the guy who own the phone can be seen in pictures) [3 : 5 : 10 seconds] – Makes sweet sounds every second.
-Image-sequence
-tinker with the While-balance & Brightness.
-Add effects like sepia.. grayscale.. b&w etc.
-Settings

• image quality, image-size (1536 X 2048 to 120 X 160)
• video-clip-length can be made maximum (depending upon your card's free space)
• 4 video resolution modes (640 X 480 to 128 X 96)
• 8x digital Zoom.

Bluetooth.
Its is good and works great. Internal Phone memory of 30MB can be utilized to transfer bulky files via-bluetooth.
It shows progress of sending as percentage when sending a single file and number of items sent while sending multiple items.
Infrared is unavailable.

Internet.
Opera mini is preloaded.
You can even use the default browser which is good.

Multimedia.
5610 enjoys a AIC33/DAC33 chip. It can play music around 20-22 hrs with normal usage. Offers inbuilt support for a variety of audio formats like aac, m4a, wma and mp3.
Videos can be played in mobile optimized formats like 3GP and MP4.

Inbuilt Flash Lite support.
you can make flash applications... swf (shockwave flash).. your wallpapers or screensavers.
How about a drizzle on your desktop! Cool. Isn't it?
You can even make applications to monitor battery or time etc.

Good Java ME support for developers.
supports Java MIDlets, i.e. Java MIDP and CLDC technology.
(I use a free dictionary made by some Maharashtrian[don't get me wrong its no way racial segregation & I'm not a chauvinist]. A Java-archive [JAR file])

A lot of games (But I don't play any... People say they are good. “City Bloxx”.. “Rally 3D”.. “Snake III”... etc)

Sensor (A bluetooth application)... to socialize and make new friends (transfer stuff).

Processor speed is around 234MHz (benchmark) and around 5 MB RAM.
Series40 uses a simpler operating system than the higher end s60 (which is based on the multi-tasking Symbian OS). Because s40 devices do not support true multitasking and do not have a native code API for third parties, its user interface appears to be more responsive and faster than other Nokia platforms.

The catch...
a) you can set any video (playable) as your video ringing tune.
b) you can set different tunes & images for different contacts.


Enhancements:
Thin-pin Charger requires around 1.5hrs to completely charge 3.7V BP-5M Battery.
Battery Backup... 1 -2 days on heavy usage. Minimal usage: 2-4 days.
3.2mm AV-jack (headset). It has a connector to 3.5mm jack (where Computer speakers can also be connected. So no need to open your laptop to hear your playlist)
microUSB slot to transfer stuff to and from the computer seamlessly via USB connector.
microSD (Multimedia Card) expandable upto 4Gigs (GB).

Well finally when I'm with this beautiful thing (which it actually is... Slider.. blue... and Lights!!Sexy... Aaah!! Reminds me of... hmm... wait-for-it... Mirror!!) & having a good time with a 1GB microSD & the microUSB. Well talking about Stuff..........

a) You can play 3GP & MP4 movies in all sizes (QCIF, QVGA) up to this maximum resolution VGA 640X480. (Trust me! You won't need anything more than that for even HDTV viewing).
& all that inside its inbuilt player - “Media Player”. No white bars on side... in full screen view. Video occupies full window.

I've two videos...(allow me to call them Movies...) full blown 80 -90 minutes in 60-70 MB.
“The Secret” & “D5 conference Bill Gates n Steven Paul Jobs”... 3GP (176 X 144 resolution and clear picture). With this incredible[right.. I really love this word.] ability to seek forward quickly to catch up from an earlier time of viewing.
How to do that....!! Well convert any possible media stream inside your computer to 3GP or MP4 through a FREE converter. Just google. I use...

ABC 3GP converter (a3gpset)... [Free] along with...
Avidemux (Klite Video Converter).. [FOSS = Free and Open Source Software]
VCD Cutter 4.0 (Jaio System Ltd.) [Cracked] – (to convert VCD files [.DAT] to MPG)
using Nokia PC SUITE is recommended. It converts them to the best possible format for your handset (You can decide the size or the quality).

b) Offline HTML pages saved through Firefox (web browser).. copied to the phone.. open seamlessly with even Images. Navigation is a hell lot easier. Nokia Series 40 phones now use this Open Source software WebKit (components WebCore and JavaScriptCore) to have support for XHTML.. HTML 4.01.. Javascript1.5.. CSS2 and even AJAX. Kewl indeed.
(Think: you can research on your computer & review it on your phone)

c) I also plan to read some books... (Nay!! Not curriculum) Like Novels.. or self-help-books.
To name a few.. I've started reading..
The Monk who sold his Ferrari (Robin S. Sharma)
Who'll cry when you die (Robin S. Sharma)
State of Fear (Micheal Crichton)
Deception Point (Dan Brown)
The Tao of Physics ( Carpa)
Psycho cybernetics (.... hmm!! can't remember this one. Some plasic surgeon)

okay.. so this shows I start reading and then seldom [get time to] complete. So as for light reading.. I've saved a few ebooks (in TEXT format) inside my mobile too.
the power of concentration
Zen and the art of motorcycle maintenance.

But there was this problem.. It can only read upto 3000 characters and truncates the rest of the text because, it has an Organizer -> Notes Application which can save upto 3000 characters in a note at a time. [My sister's CDMA Nokia has just 300 Characters limit. How Sad!!]
So what I did was I created a command line application in Java to split my text into Crumbs of size my phone allows me to read. (Find that TextSplitter somewhere here).
Now the “Zen” folder has 286 text files numbered 1 to 286. How awesome is that!!!
To ignore the downside.. you can start reading from 1 & keep removing text as you read it. & “copy to Notes” stuff (beautiful thoughts) you want to keep with you.
(Think about an SMS-maniac who keeps a note book [buys books too] to forward messages. He can just copy paste)
Talking of which... Copying Text... & pasting in some other application is entirely handy with option explicitly given. You can mark-text or mark-all.
Talking of which, selecting files.. Marking files (or all files) is also very easy. You can then send these files via Bluetooth... or delete them.. move them... et al.

d) Backup messages.. phone contacts... calendar records.. bookmarks.. user pictures.. memory card's content.. etc. Using NBU (Nokia Backup). You can restore these on account of a phone theft (Take out a minute. Its time to pray to God!!)... or Phone Migration.

e) You can even send messages from your Computer (through the phone obviously via the USB cable)

f) This phone can act like a Modem and you can use GPRS.. or EDGE (Mobile Office) to connect. Use Internet anywhere. Well this time you have an actual keyboard.

g) Transfer music & videos to-n-from phone. Conversion to mobile-optimized audio and video formats is possible.

h) There is some protected mobile content in the memory card which cannot be played without correct access codes. You can we even then extract some content using this method.
- in your computer select any mp4 file and default it to open with KMPlayer.
- now connect mobile via USB in PC-SUITE mode.
- browse and open. The content shows up in your player.
- Now right click on it. Look for an option of Save-As-Video and you are done.
- otherwise you can even capture the video. [KMPlayer is good.]


Problems Fixed...
a) mine is V4.81 (type *#0000# to see it). Earlier versions had this problem to freeze when you receive an SMS while listening to some tracks.
b) .... gotta research more to fill this further... but hey (a) is substantial.
Well you can always update your mobile software yourself through PC-SUITE.. go to “nokia-europe” website. Look for the software updates made to your handset's model. Download & apply. You are done! The problem is Fixed. Life is easy AGAIN.

Downside....
a) it gets creepy... shows distortion for a second or two (in a day or two) & sometimes even gets restarted after a creepy deep humming (once in a day while talking.. depending upon its mood & climate)
b) microUSB cannot be used to charge the mobile phone via USB slot unlike miniUSB.
c) pictures featuring me (not under daylight) are just devilish with two giant Red-Eyes when flash is on.
d) the back-battery cover gives me this feeling that it has a short life expectancy.
e) The devices themselves are locked down so that you cannot replace the factory-installed OS. So I (or even YOU) cannot install Linux inside it.
This is really really Sad. But if you have 22,000/- in your account go to OpenMoko Project “http://openmoko.org” & get freerunner. & Linux is there in Nokia 770 too & some Motorola models.

have a lot of fun.