Fanboys and schoolchildren working on the "who would win if Y fought X" will love this. Unfortunately, it is also a perfect example of how not to write in a shared world, whether professionally, as here, or in fanfiction.
Firstly, if you are going to retcon canon extensively, make sure you have given your reasons. Here the authors have picked and chosen bits of the long Phoenix/Dark Phoenix saga and dismissed the rest. It is unfortunate that the bits they have picked do not fit together. If the retcon of the original Dark Phoenix saga in 'Phoenix Rising' did not take place, and Jean Grey really did die on the moon, then, really, fellas, Jean wouldn't have married (and subsequently divorced) Scott, and it wouldn't be the Jean Grey School.
And that is just the simplest of the problems created here. I find suspending my disbelief rather difficult.
Likewise, it is not enough, when you have characters acting so far away from their normal behaviour - particularly characters like Captain America and Scott Summers - it is not good enough simply to excuse it by having another character (in this case Iron Man and Magneto) say, "Hey, you're acting like me," and expect that to cover your asses as an explanation.
As for having a polar bear in Antarctica just so you could do a call-out to 'The Empire Strikes Back' - spare me!
Setting all that aside, there is some fun dialogue, and some really nice art. Not so much on the characters - some of which look very odd - but on the splash panels.
You do get a lot for your money, though, and the production is lovely. See if you can get it discounted.