The original X-men fought as a team. Although Angel doesn't seem all that interesting in terms of what he can do, the X-men worked together, combining their powers. As someone stated before, he was one of the original X-men. From what I remember about the comic book (involving Angel) he was pretty much the only one who could fly in the original X-men. Jean Grey had telekinetic and telepathic powers that could help "fly" and Ice-man could create ice bridges. Beast and Cyclops were just stuck on the ground. So it was a good mix of characters.
When Apocalypse took Angel "under his wing," he was transformed into Archangel. I'm guessing that the movie is going to show this event if they are putting such an emphasis on Angel. As Archangel he has "metallic" wings that shoot blades, and he can also retract them.
If they do put such an emphasis on Angel then I hope they put an equal emphasis on Psylocke who, in the comic book, is Angel's woman (can't remember if they get married or not). And if they put an emphasis on Psylocke then I hope they put an emphasis on Excalibur from Great Britain (but then that would probably be asking too much).
My all time favorite X-man has always been Wolverine though. Not because of his adamantium claws and skeleton (that should get ripped out soon if they make an X-men 4) but because of his super fast healing power. I still have my old collection of trading cards. The 1990 set has a card of Wolverine and on the back is a "Did you know?" fact that says "Wolverine is actually over 80 years old but because of his fast healing powers he ages very slowly."
Hope that helps a bit.