The exceptional acting is what makes this overtly violent film exhilerating. Di Caprio and Matt Damon were great, but for me, the best actor by far was Mark Walhberg. His character was was so well written and the foul language flows off his tongue so smoothly that you truly love the character after the first 5 minutes.
Go watch it, but be ready for brutal, in your face violence, Scorsese style.