I was pleasantly surprised by Eclipse. I love the Twilight books but have been extremely disappointed in the first two movies - they in no way lived up to the books. I was not even planning to see this one in the theaters until a friend made me promise to go with her.
But I though Eclipse was pretty good and IMHO the best of the series thus far. I'm not saying it was great or one of my favorite movies but it was good. And I would recommend watching it.
I liked the movie Twilight but I was disappointed as well. For the budget they had, I think the producers/director did as well as they could. Now that they've given the go-ahead for New Moon, I'm hoping they will put more funds behind the making of the movie.
But here are the problems I have with the movie: I think the special effects were the quality of a TV movie. I think there it was a bit choppy at the beginning and 5-10 more minutes spent developing the relationship between Bella and Edward would have seriously helped. I thought Edward was too tortured.
So over all, I liked it and would see it again (I have seen it twice now) but was also disappointed and hope that they take more time with the next installment.