I do not think I did much research before I bought this one. My friends were using the 6610 and when Nokia offered the 6610i, there was a bit of hesitation, but I thought what the heck and went in for it. I have used it for over a year I guess, and its just an exceptionally good phone !
The things I really loved about this mobile are:
Its tough as a brick (probably tougher). I have dropped it a gazillion times also managed to immerse it in water, but it never stopped working. Even when it broke into 6 different pieces you just need to put them together and voila its up and running again. Brilliant !
Very very user friendly. Doing anything ane everything is as easy as eating peanuts. The options and buttons are exactly in the order that you would expect.
Battery life. Usually lasts for 3 days on a single charge.
Features. Had most of the stuff that I wanted. Radio, alarm clock a few games a basic camera. At the time this was what I wanted and this phone had it.
The keypad is amazing. Real easy on the fingers and very soft and responsive.
Frankly there really was nothing much that I did not like about this phone. The pictures are not so great, but then its just a VGA camera. I have uploaded some sample pics so that you can check the clarity. As with most mobile phone cameras, low light pics are not at all good !
Finally, it all depends on what you are looking for. If you need a basic phones with some extras (such as FM radio, alarm clock, calculator, stop watch and a VGA camera) .... then look no further. This is the best value for money for this particular feature set.
Buy it, you will not regret it. I have not !!!