You know how many movies that had trailers that didn't impress me or ticked me the heck off that I wound up seeing and enjoying anyway? It's 6-10 bucks and 2 hours. If you're a fan, you'll go and at least have reasons to complain if you don't like it. You'll either wind up enjoying the film or at least having something to pick apart.
That said, the vast majority of the fans are looking much more forward to this film than the last one. While the last film was very good, the main excitement was that we finally got a Muppet movie after MFS. This time, the excitement lies in a much more structured story that focuses on the main characters and almost feels like an original Jim Henson era concept. I'll agree as far as the last film went, Frank Oz had a point about it being safe. That was intentional to re-establish the brand. The training wheels are off, and we're REALLY going to see some unbridled Muppet action in this film. What isn't exciting?