Skipping the Phoenix Saga was a mistake, and not having the Hellfire Club, the Shi'ar, the Black Queen, and Emma Frost... well, if they put some fan service and easter eggs, fanboys will be happy.
"The Last Stand" was a big hit all around the world and nobody disliked it, X-Men comic book fans apart.
I found it a brilliant and bleak superhero movie featuring terrific sequences and great action/CGI.
Despite that, I'm glad the timeline has been revised two times, and now we will get a "Phoenix Saga" closer to the original story.
I think with genre films in general it takes a VERY special film to rate higher than 60% on the tomatometer. Problem is that the average movie goer will take those reviews to heart and generally pick their weekend viewing using the system to help guide them. Battle Angel Alita is a great example of a film that had pretty low scores but yet it's highly rated by fans of sci-fi/dystopian films.
And yet X-Men, X2, and First Class all managed to do that. X3 didn't.
Because X3 was 9 different plots happening at the same time, and the movie tried to pass that as depth. I know whose idea it was to have Phoenix/Dark Phoenix be the D-plot in a movie, but it was a bad one.