Make a painless iPhone (and for some folks - Android) + GMail sync and I'll probably pay you $10. Although, I can still sync iPhone contacts with GMail (using a payed app because MS Exchange integration is a pain in the ass), so I'm not sure. I like that it's simple, but there should be some killer feature that would make me want to switch.

But maybe I'm just not your target client. What's you target audience?