What did you expect? That will answer your questions.

Rating: 6/10 (4 May 2009)

Being an X-Men fan since the early 1980's, I was bound to see this movie. Hearing about the generally terrible reviews, my expectations were sufficiently low coming in. What did I expect -- not Tolstoy, not Kurosawa. What I got was a pleasant surprise.
Film reviews are becoming less and less critical (pardon the pun) to a film's success, especially when you consider those for genre films. There are plenty of people who will always review a horror film as terrible, for example. And most critics are not fans of the superhero genre, save those they grew up with, perhaps Christopher Reeve's first couple. Are they going to like "Wolverine"? Not likely, and not important to anyone else's enjoyment of the movie.
This is a summer blockbuster, and it works just fine. It does not, in fact, have gaping plot holes, terrible inconsistencies or many of the other easy targets that we're hearing about. Did these people see the first three (if we include the Brett Ratner misfire)? People are going to see this movie mostly for the action and the actors, but there is actually quite a good deal going on beneath the surface -- for the genre fans.
If you don't like superheroes, why would you bother going to see something like this in the first place? Don't. If you're an X-Men/Wolverine fan, it doesn't matter what other people think, you're going to see it. But for anyone else in between, just temper your expectations within the genre, perhaps do some background reading on who the characters are (you should know who Gambit, Deadpool and The Blob are, for example), and maybe even try to find some friends to go with who are genre fans.
Within the genre, it's honestly not bad. A step up from X-Men 3, a good deal better than Daredevil and Punisher, but really not close to X-Men 2 or The Dark Knight.
Finally, if you haven't seen the original three of the series, it's quite fine to see this one first, you won't get any spoilers from Wolverine.