I have an Apple 3G iPhone with the 16G hard drive. LOVE IT LOVE IT LOVE IT! Dont know how I ever lived without it.
The Weight Loss apps have helped me lose 14 pounds so far, and I would hardly ever get on Facebook if it wasn't for my phone. I play games on it, watch movies on it, and work out with it. I have my grocery list on it, and I check the weather, and find my way arounbd new towns with it. It's very stable, and hasn't locked up much at all.
It's incredibly easy to use, basically, swipe and pinch.
Oh - it makes phone calls too.