I haven't been reading any reviews or detailed impressions online before seeing the movie this morning, so forgive me if I'm rehashing things that have already been said.
It was OK.
There were some really good moments throughout the movie, but they were buried under a movie that was overstuffed with characters and storylines. I'm mildly positive about the movie because of those moments, but somehow with everything else on the screen it all adds up to a movie that is less than the sum of its parts.
If X-Men: The Last Stand was made up of 4 movies smashed together where maybe half of one of them was OK, X-Men Apocalypse is made up of 4 movies smashed together where maybe 2 of them were OK. Add in some bias from me as a lifelong X-Men fan, and I would rate this 3/5.
Spoiler details below: