1. Longer Running Time:
The movie felt rushed at a lot of parts, and it needed to be fleshed so we can taken in what exactly was happening. Give young x-men more lines and scenes. It needed character develoment as well.
2.Cyclops being alive:
his death was pointless, and wasn't handled well at all. It was like poff his gone, let's move on. Cyclops's desreved to have more screentime, than that!!!
Some of the characters lines didn't match their personality, and it felt forced!!
4.Too much editing:
There were too many lines and good scenes that were cut out of the movie, making to disappointing at times!!
Fixed those things, and it would have been damn near perfect!!