A solid 8. It had a lot of great content, and some big surprises, plus a few expected-but-anticipated announcements.
But it could have been better. Even a first hint of the next main Pokemon title. Some hint of one of Nintendo's lapsed (that is, not yet on Wii U) franchises (Metroid, F-Zero, Endless Ocean, etc). New content for Mario Kart 8. A new Wii U title (not just a port).
Basically, there are a lot of ways Nintendo could have made it a 10. But it just didn't quite get there. But an 8 is still very, very good.