This is exciting. I trust Kevin Smith's opinion, but then again I trust Leonard Nimoy's even more and I've been excited ever since he said, "this is going to be a great movie and I don't say that lightly."
Frankly, I don't trust anything an actor says about a movie that actor is in. They have a vested interest in how well the movie does and are a part of the movies' promotion machine.
As others have pointed out, Smith could have remained silent about the movie. But from reading the interview it sounded to me like the little Star Trek faux discussion was set up in advance -- like he wanted to talk about it and told the show's hosts so they would lead him into it.
I may or may not agree with Smith after seeing the movie myself, but for now, I consider him as objective and informed an opinion on the movie as is currently out there. And because his opinion is positive, I'm kinda geeked.