Having played both classes to 13 in the beta, the Monk seems to severely lack in both gameplay and damage. Especially with the constant Monk nerfs, I cannot see how one will enjoy the Monk more than the Barbarian. Barbarian does what the Monk does, but better!
The spirit generators for Monk have been nerfed and it just seems that you are struggling to build up spirit; whereas the Barbarian seems to have excess rage almost all the time.
Also, WTF is up with Wave of Light. I know bells 'monk-y' but the design, animation, damage, and 100 spirit use is just unbelievably bad.
Now I know we haven't seen how spirit passives, gear will play into mid-late game, but it's not looking so good imo.
There are MULTIPLE threads on various D3 fansites (including battlenet), but I think at this point, it's too late to give Monks any significant changes.
Not to mention the animations on the Monk skills are very mediocre. I'd expect a lot more from a game that's been in development for so long.
Some interesting threads: http://www.diablofans.com/topic/3661...n/page__st__20