One of the new features on the iPad 2 is it's full mirroring support. Unlike older devices, the iPad 2 can mirror everything you do on the screen instead of certain apps. This is a big help to people who use their iPads to demonstrate something like a project or for developers, APPS!
The mirroring feature does come in handy while playing games, but unless you have a long HDMI cord, it's going to get a bit annoying. Games like Real Racing are fun since you get to use the iPad as the controller and don't have to look down as much with simple controls. But other games like Angry Birds make it a bit pointless since you have to look where your thumbs are.
So if you are someone that watches a lot of movies on your iPad and your TV this might be good for you since you can project them on your HDTV with this method. In the end, you really have to ask yourself how much you will be using this, and if it is worth the $40 for you?