One thing that is really nice is that as long as you use the stick control on NHL 2K9, the controls are very similar and you can easily go back and forth between the two games. It wasn't so easy to do that with NHL 2K8.
I like the 2K9 controls a little more since you use the right-stick to control your stick on defense whereas you need to use a modifier to control your stick in NHL 09. NHL 09 uses the stick to control checking on defense . . . which seems kinda silly because why would you want to check empty space? (I guess the stick let's you control which direction you check if you are really close to two players, but that situation is pretty rare and you want to be be checking the guy with the puck or else you are committing interference.)
NHL 2K9 managed to keep the super-star moves but they are kinda hard to use in the game since it is so fast moving. However, when you are able to pull one off on a break-away, it is pretty satisfying. I like the fact that when you are waiting for a game to start in 'team-up', it puts you in a shoot-out practice mode so you can practice trying to pull them off.
