I've never used Gamecenter until last night, but I was pretty happy to find out that it's available for Apple TV. I was skeptical at first of the quality of picture I would be able to stream, but it was extremely solid. It's not RDS in HD, but it was watchable on a 46" HD screen.
The first thing I did when checking out Gamecenter was to look at the NHL Vault™, but unfortunately that's not available on Apple TV, that app sticks to modern games only. Perusing through the Vault, I noticed that the game 7 against the Penguins from 2010 was there, so of course I watched that.
There are some quirks you have to get used to with Gamecenter though. Any game that is broadcast locally or nationally in your area will be blacked out. This is brutal if you don't have cable, but luckily I do so it's not a big deal.
While the video quality can gust up to HD if you have good internet, the audio always sounds a bit off. Crowd noise especially can be grating.
All in all, not much to complain about for a free service (for us, it's still $50 regularly), and the ability to revisit games from this season will allow Chris Boyle so keep doing his Carey Price game reviews, which is awesome.