Firstly let me say, despite everything I am about to say, I enjoy the game.
That being said, this game does have several issues, so lets look at my opinion on the pros and cons.
PROS:
Combat feels good, the mechs feel big, stompey and all in all the game play itself feels satisfying.
With a variety of mission types available, there is a good variety of play options, and if you like mech combat, you will enjoy the gameplay.
The Coop options is a lot of fun, and being able to go into battle with Real Life lance mates is a blast.
CONS:
The storyline is shallow and brief, and feels like it was rushed. Some of the story missions feel polished while others feel like after thought fillers.
The AI (especially your lance mates, even at max pilot skill levels) suck. For example on defense missions where you have to protect a base, they often stomp through the base and destroying it in the process.
They also sometimes make poor weapon choices in combat and the order system leaves a lot to be desired.
There are also a few quality of life features that are lacking, and could be implemented easily, to make the overall experience.