Making a bit more use of the graphics, I've downloaded rather a nice pinball game in Pinball HD. Only 3 tables, but a good variety of types. I confess I've always been a sucker for pinball in its physical incarnation, so the excellent look and feel of this game appeals a lot. The only slight surprise, given those motion sensors, is that you can't tilt.
Finally, I've had a quick go at the (free) opening section of the new Back to the Future game to see what leading edge graphics in an iPad game are like. Although I found the exposition of the story a little slow (you can swipe to hurry it up, through), it's a nice combination of an interactive video and a puzzle game. It looks good and it plays smoothly.
I haven't tried any shooter games yet, but on this early sample, games and the iPad go together well. I bought it thinking of it as a toy and it has proved much more - but it doesn't mean you can't have fun with it too. There are plenty of free games, and even those you pay for are rarely more than a few pounds - very refreshing if you have been paying £30-40 for a game.