Yes, there have been cops and robbers movies. Yes, there have been `buddy-cop' movies and yes, there have been a tonne of movies where the protagonists fall foul of the mob and end up `owing them big-time.' However, very few of those manage to pull of those generic plotlines off in one movie (and, more amazing still, make it work).
2 Guns is nothing original, but it is fast-paced, slick, stylish and, best of all, entertaining. This is probably down to the two leads - the ever-reliable Denzel Washington and the mainly-reliable Mark Wahlberg. Perhaps without these two heading the bill, the film would have been as sub-standard as the plot suggests. The two actors play off each other brilliantly and save every scene from ever slipping into mediocrity. There's a real `Pulp Fiction' vibe between them with all the banter and general chit-chat which helps establish their characters.
There are plenty of good performances from the supporting cast, too. The long forgotten Bill Paxton (still best known for `Hudson' in Aliens) is great as the villain.
Basically, if you like cops and robbers, crime, gangsters, or just generally action movies, you can't go far wrong with this one. Grab the popcorn, ignore the odd plothole and just enjoy the ride.