Over all I don't think the monk is too bad.
The BAB, while not the best, is also not the worst. I mean bards, rogues, clerics, and druids can do alright in combat and they use the same table, only 5 less than a fighter, paladin or barbarian at level 20. No biggie.
Plus, the UAB provides even more attacks than those classes.
You can increase chances of hitting by picking up Weapon Finesse (Unarmed.) More than likely you are going to already have a decent Dex since you can't wear armor so this makes the stat extra useful.
A monk's damage isn't stellar to start out with granted, but it's also not god awful. Average at first, at the higher levels, though... The only problem with this is overcoming DR.
This is addressed in part by Ki Strike allowing the monk to use their unarmed damage or they can use an enchanted monk weapon assuming they don't want to sacrifice their attack rate.
The problem here as mentioned previously is that they sacrifice damage to do this.
The other option in this case would be to use gloves or leather straps that were enchanted with weapons enhancements. In fact I do believe that I've seen those in one of the WotC books. Flaming fists anyone? Use your UAB, increased attack bonus from Weapon Finesse and a decent dex, and still get to use your unarmed damage. Oh yeah and whatever bonuses are on those gloves.
Now many would think since they don't get to wear armor Monks are bad off in this department. More than likely they are going to be somewhere around the level of a barbarian, ranger, or rogue as far as AC. For example say any of the previous three classes were wearing enchanted +5 chain shirts to stay within the light category. At best they are going to have a bonus of +13 from armor and dex (4 + 4 + 5).
A monk could throw on some bracers of armor +8 and assuming a wis of 14 and dex of 18 (not unreasonable I think) then they would have a total of +14 to AC (8 + 2 + 4).
A fighter, paladin, or cleric could easily beat them on AC but then again they are wearing plate and possibly large shields.
Again they aren't the absolute best, but better than a majority of the other classes. And that isn't even an extreme example using dex and wis enhancing items.
Speaking of dex and wis enhancing items this is where the monk definately beats out any class. What else does wisdom affect? The Will save, a very large hole in the defenses of the majority of classes. The enchantment school of spells can be worse than a fireball anyday, fireballs just damage or kill you.
Now speaking of fireballs a higher Dexterity also affects your Reflex save. Traps or area spells that might heavily damage a party may leave a monk completely unscathed.
While thinking of saves, combine the higher dex and wis bonuses of a monk with their fantastic saving throw bonus progression and you've got a winning combo.
Now if you want to do some minor munchkinizing, play a LG monk, and assuming your DM allows free multiclassing for monks and paladins toss in a level of paladin to get that charisma bonus to saves as well (or just start with a level 1 paladin then switch to Monk from there out and thumb your nose at the DM). These guys can be fun and easy to roleplay too. Honorable and holy monks fighting the good fight. Zen and the Art of Quelling Evil.
Add on top of all the other special abilities that a monk gets and frankly that's all just some nice icing on the cake.
Never really thought it all out before...now I'm wondering why I've never played a monk.