I kept my BB Curve along with the iPhone. So far there are a variety of things my BB and do that my iPhone can't, like:
-cut/copy/paste
-save and edit attachments
-configure the camera
-profiles
-push email from my Gmail accounts
-tons of easy to use options
-ability to make TASKS
-ability to schedule items in different time zones
-voice dialing
-A2DP
-mass storage mode
-3rd party apps
-many more
However, the iPhone is very good for it's initial release and I'm sure it will be getting some updates soon!