I am using this for the past 3 months now; bought it from Viveks on CMH road (bangalore) for 10000 that time. I guess the price is reduced to some 8500 now.
Model resembles 6610, differences are 6100 has no FM radio, but is more compact.
The look is very good, slim good screen etc. sound quality is one of the best I have seen.
Java applications are supported. Already it comes with a currency converter and world time clock.
Tones are similar to 6610 quite ok. vibrator is also satisfactory.
It weights only 76 grams (including battery). size also is quite small ? 102 x 44 x 13.5 mm.
Phone has 725 kb of memory and the phone book can have upto 300 entries.
Battery life is quite good. you get upto 3 hrs talk time.
You have only 2 games. out of that chess is quite unplayable!!
You cannot assign pictures to a phone number. you can assign tones only.
The display is slow while typing fast or moving from menu to menu.
You can not send ring tones from this mobile to others.
Phone does not support bluetooth only infra red.
I guess there is some problem in the software, it crashes often. I checked with many people and almost all of them have experienced it at least once.
If you take it to Nokia service center they will reinstall this and give it you free of cost. This is a known issue with this model and also 6610.
We can compare it to MS windows. Very user friendly but needs some occasional patches and service packs to avoid crashing !!
Overall a small stylish phone nothing much.