That's just what the reviewers did. They compared it to GTA

.
There are a lot of similarities so it's not too bad to compare the games.
However I compared to something along the same lines JUST CAUSE which is vastly superior to this mess.
The biggest problems with Merc's 2 is the hideous level structures. The fact that when you die mid mission you are often sent back to the PMC and have to travel half the world if you haven't got a heliport located near to where your mission lies, and then just when you get there your hit by a rocket from out of no-where and have to do the whole thing again...
It's simply atrocious that it's level design is stuck 6 or 7 years in the past when games have moved on.
Even one of the earlier missions when you get the buggy and have to drive from checkpoint to checkpoint in the mine should be fun, instead it's design is awkard, labored and simply NOT enjoyable. Then there are other irritants such as - hey its ok to drive full speed into oncoming traffic or a tree - however you merely 'touch' one falling log and your car explodes ? WHAT? This is just BAD BAD DESIGN.
And that's where the problem with Mercs lies mostly in it's design which if it play's as it was created means it was just a labor and not a labor of love.
Then there are the hideous other bugs such as enemy soldiers who can happily run 'inside' rocks and call for air support but they can not be killed or stopped because they are stuck inside this impenetrable clipping paradox.
All the bugs, all the irritants could be forgiven if the game was fun but it just isn't. Its a poor enough joke that you may have smirked at the first time you heard it - repeated ad infinitum. To the point it becomes almost unbearable.
MERCS 2 IS POO IMHO