They did a really amazing job showcasing all the different powers. And speaking as someone that's not really that familiar with the comics I didn't feel like it was that difficult to follow all of them even if I didn't know the names of most of them. Mostly because the new mutants aren't really there as new major characters, so there's not a need to get to know them too much. You get to see what they can do and you get to see them being awesome with their powers.
Also, I'm not enough of an X-Men fan that I understood the post-credits scene. Luckily I was with friends that know much, much more about X-Men than me, so now I'm super excited about the next X-Men movie.
Going in I was a little iffy on the design on the Sentinels, but actually seeing them in action was pretty cool, especially the future versions. Those things were pretty terrifying.
Sometimes the scale of Magneto's power is kind of annoying. Like he was buried however many feet underneath the Pentagon and there was no metal in range, but then he was able to stand in the middle of a stadium and lift it up. As awesome as it was all I could think was "if he can reach to either side of the stadium with his powers, then it's hard to imagine there was no metal in range when he was imprisoned. But, whatever. That's minor and Michael Fassbender's moments as Magneto were great.
Seeing Blink in action was super awesome. All I could of was "NOW YOU'RE PLAYING WITH PORTALS". That was really awesome to see on screen.
And Apocalypse! Like I mentioned above I didn't know who it was initially but once my friend explained who it was I got pretty excited. Definitely excited to see that storyline play out, presumably in the next X-Men installment.
I imagine some people will be upset by the retcon that basically happened because of the time travel stuff, but that doesn't bother me, especially if it means bringing back some classics like Cyclops, Jean Grey, & Beast.
I'm sure I have other thoughts, but I was up late because of the release-day showing. But, yes, I really enjoyed the movie. I'd feel pretty safe saying it'll be the blockbuster of the year.