See this movie in context and it's epic. See it as a stand-alone film, and you miss the point

Rating: 9/10 (28 May 2016)

"Promise me you'll find us...the X-Men...guide us."
This was Logan/Wolverine's plea to a young Charles Xavier/Professor X in the previous installment of the X-Men franchise, Days of Future Past. That film essentially gave the franchise a fresh start, free of it's past mistakes (ahem,The Last Stand, ahem). Now, we get to see what director Bryan Singer can do with his second chance.
It's 1983, exactly ten years after the future-changing events of Days of Future Past. Xavier's School for Gifted Youngsters is full of students, Eric Lensherr/Magneto is living low in Poland with a new family, and mutants, while not openly persecuted, still feel like outsiders.
Along comes En Sabah Nur/Apocalypse, played by Oscar Isaac (Poe Damaran, is that you under all that makeup?). He's the world's first mutant, buried in stasis in Egypt after his subjects betrayed him 5000 years ago. Now he awakens to a world that doesn't worship any one god (read this as 'him'), and he sets about to fulfill his name, with the help of his Four Horsemen (Magneto, a young Ororo Monroe/Storm, Psylocke, and Angel).
Faced against the end of the world, Xavier and his students must band together and fight, as Charles states: "Those of you who have the greatest power, protect those who don't."
This film is basically the X-Men version of The Avengers. Most people familiar with the X-Men films know who the major players will be, and here we see them as separate people with their own problems who will come together to protect the people of the earth (at least X-Men aren't squeamish about saying their team catch phrases on screen, unlike some.)
Now, for those who are seeing this as their first foray into the X-Men universe: don't see this film yet. The plot will seem incredibly shallow without the character backstories that have been established, and in some cases rewritten, over the past 15 years.
The reviewers who saw this early clearly did not have this mindset. However, I have to concede some of their points that, yes, the dialogue seems somewhat repetitive and dull at times, elements that are repeated from previous films seem cheaper and less fulfilling the second time around, and there was really no feeling of suspense. But honestly, this is a superhero movie, are there really any true shockers in those?
In short, you won't regret seeing this film if you are a fan of the X-Men franchise. The last film erased their mistakes. This new one is not a new mistake, but they now have no room for error going forward.