Here’s why you SHOULD watch this:
The stylistic choices are amazing. It's packed with slow motion, perfectly shot, cinematographic action. There's bullets extruding from peoples heads in full graphic glory. Cars flip over in slow motion, while characters mouth wise comments. The visual and audio effects really transport you into scenes. For example, when Wesley is having a stress attack, the pounding heartbeat and pulsating screen, cut between his red throbbing face, are just a taste of the action for when people are honing in on other, much cooler, stuff. There's just a little humor to keep it going, but not like full on Deadpool.
James McAvoy is amazing. His expressions explode and you really feel the tension. Angelina Jolie is also quite good.
Here’s why you SHOULD NOT watch this:
The plot is so bad. Not only is it bad, it made me actually go from this is obvious to "oh there gonna do that, thats kinda dumb" to actually laugh with what the heck was that. It feels like they thought they were making Inception and everyone’s mind was gonna be blown, but it’s more like Fast and Furious where they try so hard to make drama and all you can do is cringe and wait for the next car to explode. Ok, it’s not that bad. It’s a fairly decent plot. But this is worse than F and F because this is NOT dumb action and the plot is not so much something that can just be ignored, so the weak parts really hurt the movie.
In summation:
Watch for the cool action, partially great acting, and parts of the plot that are quite enjoyable, but be prepared for weak motivations and just a little disappointment.