I had the Nokia N73 and replaced it with the C902 in July. I personally have had a horrible experience with the C902, the keypad has actually fallen off, the phone is slow, it turns off randomly, freezes every now and then, it's terrible.
My brother on the other hand, got the Samsung Tocco (I think that's what it's called) in July and he's loved it and i've got to admit, it's pretty snazzy. It's a touch screen phone with a good camera and seems to be reliable.
I wouldn't get the iPhone personally, it's too much like the iPod touch...I'm just one for the Sony Ericssons. My mum got the C905 the other day, have to admit, it's impressive. Much better than my 902.