A: Where's the Sentinels? I was expecting to see them fighting with the mutants (a lot of actions like we saw at the end of The Avengers, which is pure awesome!). If Singer is saving the clips of Sentinels best for last, then I understand. We, the fans, DO want to see a lot of actions from big robots, though! C'mon, make it happen.
B: I seriously hope Singer is not using Wolverine as a person who travels past/future. In comic, it was actually Kitty who traveled and warned the past X-Men about what will happen in the future. Dear God, Singer, seriously, please study the comic book more carefully. Do not screw it up!
C: I hope it's not another "boring"/"forgettable" story. Admittedly, the first 2 X-Men movies, which Singer directed, was "meh", in my opinion. The third one, with a different director, was worse. I'm trying to forget it like it didn't even exist.
D: Please focus on a big team, not just Wolverine. I felt like Wolverine stole 85% of screentime in the first three movies and I was very disappointed. Where's the focus on developing the characters of Cyclops? Storm? Gambit? Or even Kitty? Although Wolverine is my #1 superhero in the whole world, I'd still like to see more of screentime with other X-Men members as well to make them more "likeable".
E: Since this is a huge movie with so many characters to play with, it needs to have more space. I'm talking like 2 hours long movie. Not 1 hour 30 min crap.