Basic phone features /dimensions you can and would have read on various websites
let me straight jump in to my experience
I found this phone has a lot of pluses - things which you had never seen or experienced in any other phone so far, but at the same time lacks a lot of std phone features which are there almost in every phone today.
pros
Great sleek design
Excellent disply - same photo on laptop may not look as good as it does on iphone
Unique browsing experience - tilt the phone by 90degree and the page automatically reformat to landscape mode from portrait mode... without you touching a single button
ipod
wireless support
very fast and responsive
8gb space
usb charging as well as socket charging ( charger included in std kit)
WOW factor / snob value :) - the fact that it has not been launched in India make its better. Pull out iphone in any meeting / any party and see the effect. I have had guys walking upto me and asking to touch / hold this phone.
cons
sms application is pathetic - crashes every now and then, you cant forward an sms using inbuilt application
no video camera / no flash / no night mode / cant capture good photos of moving objects
speaker phone is not loud enough ( I was using n72 and 6630 prior to iphone.. and iphone is nowhere nearby)
phone features are not great ( you cant send a buisness card, you cant insert a number from a contact in a meesage)
gets heated a LOT while talking ( not while playing music though)
battery drains out relatively fast
you loose network coverage very fast - better have a voicemail message to keep track of calls you will miss
i am using it in Delhi airtel network - gprs is working fine, wireless LANs make it even more powerful browsing experience ( auto discovery , and auto login for known networks).
I dont think that anyone would make a mistake of upgrading the firmware - as it is a known fact that doing so will cause your phone to stop working - till the next version of ibrickr/jailbreak is available.
Officially you were supposed to use the inbuilt tunes as ringers or buy online from itunes - but I am using a hindi song from my desktop as the ringer (thanks to ibrickr - a free software).
incidentally there are good free softwares available that let you sort a lot of problems that are there with this phone - even if you are not a techie.