I just saw it yesterday afternoon. Still haven't seen Spiderman yet. Took the day off after finishing a huge work project.
I gotta say it wasn't as good as First Class, but but way better than Last Stand, or Wolverine Origins. It was great to see Sentinels finally, and awesome to see Iceman in full power, in a battle and others. But the sheer quantity of characters made up for the lack of substance. No real substantive introduction to some characters like Bishop. Other than their powers or in some cases their names too, like Blink. This movie might work to some extent for comic fans who already are familiar with the characters, getting to finally see everything they could possibly want in an X-men movie, (including the end of credits scene). But some characters got seriously shorted. I'm guessing some like Anna Paquin were even just CGI. But there were so many new and old characters, and multiple versions of some, that if not for a few slow parts, you might never have had time to even think about it.
The end of credits scene was one of the best parts of the film. It was just like the rest of the film, a nice tease of a great character but nothing more.