I had an iPhone for 18 months and here is a list of stuff that CAN NOT be preformed with the iPhone:
1) Can't customize
2) Can't get apps outside the app store
3) Can't tether
4) Can't record video (3g)
5) Cant zoom or flash on camera
6) Barely any menu options
7) Very limited multitasking
8) No insurance through ATT
9) Bluetooth is only good for connecting a headset
10) You can only send one picture at a time in an email
11) Can't expand memory
12) Can't change battery
there are more... those are just off the top of my head issues that i hated and tried to live my life around... not anymore though