I liked X-men and X2. I was disappointed in X3 but I'll watch it as part of the series. I just watched Wolverine for the first time last month and it was ok. Just saw First Class last weekend and it was great, back up to X2 levels of quality.
What I don't understand is why people who dislike a particular movie repeatedly post in threads about that movie, continually arguing with anyone who liked it. What, are you trying to convince people who enjoyed the film that they're wrong? When there is a thread about a movie I didn't like I simply avoid that thread. Maybe I'm strange though.