Until I got my 9700, i would rotate between my curve 8310 and iphone 3g. Not sure you could compare them. I like having buttons to type on. I never had an issue with the battery, but lack of removable battery irked me on the iphone. My wife swears by hers, I use mine as an ipod only now and keep it in my bag or in my office.
I love the 9700, the data feature is the winner for me. I like being able to talk on the phone and chat in yahoo if i want. Battery life is amazing on the BB's compared to the iphone as well.
Personally, i'd chose the 9700 all day long, but my wife would chose the iphone, depends on what you want to do and what you like.