The Guard is essentially a screwball comedy wrapped in an Irish gangster movie blanket. The dialogue is incredibly fast paced and witty, with the performances matching. Everyone involved, led by the always fantastic Brendan Gleeson, is on board and looks like they are having a blast.
This is not as tightly constructed or written nor as serious as something like obvious comparisons such as In Bruges, Layer Cake, or Lock, Stock. However, I really don't think that it was trying to be that way.
A worthy entry and definitely worth checking out if you are a fan of the genre.