I saw it tonight and was not super impressed. The camera shots, costumes, casting, even acting seemed passable, but the writing was bleah and the movie was so long.
There seemed to be a running theme of people waiting until the last second. The Egyptian rebels might have had a better chance but they waited so long to hit their pyramid scheme (haha). I guess they thought Apocalypse needed to be on the bed to have a chance of succeeding? Later, Quicksilver saves people at the last second (but it's not his fault). He's still not fast enough to save Havoc, and he mentions not being able to save Magneto's other family. Still later, Jean sits around the entire fight, until Charles literally starts begging her to help, and then she's finally like, "ok time to help mentally, and also walk in slow motion to wreck Apocalypse". Magneto waits until the last second to think, "OK I'll actually save my ex-girlfriend and only remaining child."
Regarding characters, I don't think stuff like Jennifer Lawrence's much-maligned acting was an issue, though admittedly I have a crush on her. However, what was an issue was Apocalypse choosing Magneto and the world's 3 most useless powered-up horse(wo)men.
Psylocke had a cool sword/whip. She was a bodyguard...and never did anything. Then when it's time for her to bodyguard, she's immediately kidnapped / follows the dude who threatens her employer. She cuts a car in half to save Storm -- that was useful. And she cuts open the X-Plane and survives falling out of the plane, which is impressive. But then she has a fight against Beast, and it's basically because Beast is punching way above his weight limit and everyone else has flight, teleportation, or mental powers. And even then Beast gets almost choked and then throws her into a building or something.
Storm can pull down lightning (all of which misses) and generate a duststorm (which bothers no one) and I guess use wind to toss a car...which immediately gets tossed back. And then she apparently runs out of wind and can't fly or do anything but watch in horror until Psylocke cuts it in half.
Angel is...a flying guy. And then he's a powered-up flying guy with throwing knives. He uses his powers to cut himself free from a cage, get into the X-Plane, and die. That's pretty much all I remember. He even got special tattoos and nothing happened as far as I know.
Oscar Isaac is normally a very impressive actor, but I wasn't feeling the Apocalypse performance. Perhaps it's not his fault. Partly the costume looked so weird and unimpressive. I liked Vision better. Plus Apocalypse's writing is over the top, and even with all his killing I didn't feel he was very intimidating.
The Quicksilver scene was my favorite part again, and Quicksilver in general was awesome. I really like this version of him and his personality. It's the first one I can remember that isn't evil, bratty, or both.