I am new on the smartphone bandwagon (just got my iphone a week ago)
Dh and I were pay-as-you go customers... he with Virgin, me with T-Mobile, so when it came to "plans" we were starting from scratch.
Didn't even look at T-Mobile because they have Terrible reception in my area. It wasn't just me, either. Worked great in my old neighborhood accross town, but over here NO ONE carries T-Mobile.
In the end, I ended up with ATT. They have a family talk plan for $59/mo, AND I get a 21% corporate discount off that. I get mine because I work at Target, but they must hand these out like candy, because my dad has one and is self employeed. I'll never use all 550 minutes (which rollover) because mobile to mobile, nights and weekneds are free.
Back to what you were talking about. Data plans start at $15/mo. I picked the smallest data plan because the iphone (others do to) have wifi. So if I am at home, at the dance school, at another wifi hotspot, I can do my business for free. The only data I use, is a quick look at email, etc... on the fly.
Apps that came with the phone have served helpful already. I plugged in my contacts, names and addresses. Tuesday we went to a scout meeting hosted at a house I hadn't been to in a year. Got twisted around in their crazy neighborhood. Pulled up their name, and google maps (free, NOT navigation) found me (I was lost) and how to get to that person's house.
The other reason I wanted a smart phone, is to have an all in one device. I never have my camera on me when I want it, kwim? And I need something to keep me busy in the Dr office, and apparently, sometimes I need a map
So rather than carrying a magazine, a camera, a key map, oh yeah, and my cell phone, I can just carry my smartphone
So for me, the smartphone jump has been worth it, and the $15/mo will do me fine.