There are better phones on the market with better reception and battery life but IMO the is not a better smartphone than the iPhone.
Simplest to use, best OS, best/largest App Store, best quality build, camera, and video.
There are many good cheaper smartphone but none I've used are as good as the iPhone. Also worth noting is the iPhone is due to be upgraded in a few months (July usually I think) and the next iPhone 5 is said to be a big jump specs wise as the latest iPhone 4 is just an 3GS with a better screen. Better graphics, dual core processor and the much anticipated iOS5 will make running apps a lot smoother so worth the wait IMO.