I think it depends completely on HOW you play the Monk. I've never seen a Monk who could match a well-made armed fighter-type in a slugfest, not that its impossible though, but there's no class (well, if we don't include psionics) that can match a Monk's mobility. So, for hit and run, snatch the artifact, dash in and grapple the caster...Monks are great. For stand on the front lines and hit those enemies...I've never been impressed.
That's my take on it.