MarkB
Legend
For me their offense have never been the problem, its their defense. Unless they have very good stats in dex and wisdom their AC is terrible compared to other martial. And unlike rogues and barbs they don't have ways to halve damage. They have their extra dodge but that burns ki very quickly.
I find they suck down healing much more quickly than other martial classes, and unless they are pouring ki into defense they don't have the longevity.
That, and their mobility tends to be a two-edged sword. It's great for engaging enemies quickly, but it makes it easy for the character to get out of position compared to the rest of the party if you're not careful.