I'm a big Mike Meyers fan, but the Love Guru trailer looked really weak to me. It seemed like a funny 10-minute sketch that probably shouldn't be stretched out into a full-length film.
That said, I thought the original Austin Powers looked lame, too, until I actually saw the movie and laughed my ass off for two hours. So maybe it will be better than expected.
I was the same way with Austin Powers, I was highly skeptical from watching the trailers, then I loved it. I think this will be similar for many people. The trailers basically just display the premise and some cheesy comedy (Mike Myers winking and whatnot), so I don't think the entire movie can be judged on that. I just expect this to be a silly, amusing comedy. It's not going to be high art or anything, just a dumb comedy that makes me laugh like Mike Myers usually does.