I have been using iPhone (3!) since summer of 2011. I don't have an expensive media plan so I use wifi at my house or wherever free wifi is available.
I use the camera & video a lot. It's so nice that you can take pictures & videos of my kids and send e-mail to grandpa and grandma.
One of the things I do with my phone is keeping track of dinner using notes. I cook almost every day. It's nice to write down that info so that I don't cook the same thing twice in a week and it's good brain training.
Soon I will be eligible for the new phone. I can't wait to get iPhone 4 or 5!