I wish people would stop comparing the movies to the comics, because they are quite different! I am an avid fan of the comics, but i only got into them after i saw the x-men movie. This movie is not being made simply to please the comic fans... If anything, the fans are the ones complaining about it!
When thinking in terms of movies, the closer to the comics in dialogue and action this movie is, the more likely it is going to flop. That is what made the other two movies great. I know we all like it, because we are all fans of x-men, but do you realise how many people are dying to see this movie but know nothing about x-men? I really really wish i was one of them...
The X-Men movie verse is unique and fantastic.... i wish people would stop saying things like "Where's gambit? Cyclops cant die! Sentinels s hould be everywhere! Lets have x4 with apocalypse". That is not how Brett Ratner wants to do the movies. Brett isnt trying to fit as much x-men lore in as possible, he is trying to finish telling a great story. Just think how real the movies have been so far... The first one was about the conflict between mag's and x's opposing views. The second one was humanity freaking out and lashing out (via stryker) and this one is all the conflicts coming to a head. The human conflict is present with the cure and the mutant conflict is there with the brotherhood.
There is no way at all that this movie will be cheap thrills. If we have gathered anything from this movie via info from ratner, its that this movie has more depth and is more emotional than the others! And obviously the presence of mutants like juggernaut, multiple man, beast and angel mean there will be lots of action too...
It will not be that hard to establish these new characters, and they are not just cameo's.
The whole plot revolves around leech, which would be a bit more than a cameo. Collosus in X2 was a cameo, but in a movie centering around a war i think a soldier is more than a cameo... Multiple man, arclight, quill, juggy, dark phoenix and callisto are the brotherhood mutants who are highlighted, so they are presumably more than a cameo. The hundered or so other random brotherhoods are the cameos in this.
This movie will be good, you can already tell. But like anything, if you spend weeks and months overanalysing it b4 you even see it, your setting yourself up for disappointment. I wish i could erase everything i knew about this movie so i could just sit back and be nicely surprised by everything and enjoy a similar experience to when i first viewed x-men in 2000. That would be bliss.