Honestly, I'd give it a 7 too.

I judge these things by 1) amount of gameplay, 2) attractiveness of gameplay, and 3) pacing and overall duration.

Nintendo showed a lot of gameplay trailers and footage (too much, in fact, when it came to Smash), its collection of games looked attractive, and it was a snappy 40-45 minutes -- around half the length of the grueling Microsoft presser.

So that's a solid 7 in my book.