Attacking at Right Angles...
When it comes to direct 'force vs force' melee combat, the Monk just does not do too well. Against Monsters (Dire Animals, Trolls and the like), classed warrior types, and any other melee focused creature, the Monk will not cut it without a great deal of help. Here are some reasons for it.
1) Crappy AC - Without a great deal of AC buffing, he is a pin cushion.
2) Low BaB - He will miss against High AC, and will fail opposed attack rolls against Fighter Bab progression.
3) Unimpressive Damage - Unarmed attacks dont really get much in the way of a + to hit without a Magic Fang. As a result, you can only count on Str bonus.
I have read the term "Monk Lottery", which sounds apt. You miss often, and when you hit, the difference between rolling low and rolling high is great. After a point, Fighters, Rangers, Barbarians and Paladins have more + to damage then what they can score from their dice.
The flip side though, is that a Monk can do quite well when attacking and defending at a "Right Angle" to the situation at hand.
1) Stunning Fist: Opponent is easier to hit with successive attacks and loses his action.
2) Improved Trip: When it works, the Monk gets a +4 to hit, a free attack at the Bab that pulled off the trip, and the opponent generally cannot full attack since getting to your feet is a move equivalent action.
3) Very Mobile: A Monk can almost always get away from or get in close to enemies that are a threat to it with high movement, Dimension Door, or going Ethereal. Also, the Dodge chain of Feats is almost always a given, so Mobility further reduces AoO.
Still, there are a fair number of things that just dont quite make sense to me about the Monk. Monks get Concentration as a class skill? WHY? Other then one epic feat that uses it for an alternate Sunder, why would a Monk burn any points on Concentration?
My only real complaint about the Monk is that it is way too dependent upon Buffs. With the right set of Buffs, they are godly, but without them, they just dont quite cut it.
END COMMUNICATION