I think it would be a nice idea to discuss the usefullness of the various combat maneuvers. Clearly some are less effective than others, and some have other implications.
Let's start with the Core Material first, in alphabetical order:
Aim
At low levels, and in certain situations, this offers a decent trade-off. You lose one full round for a +2 to a single ranged attack. At low levels you lose only one attack so it's no big deal. In fact, it may be a maneuver more often used by NPCs.
Bull's Charge
Now this is idiotic in most cases: draw an AoO for a +2 to damage? Since AoOs are resolved first, and hit most of the time (remember you are charging so you have -2 to Defense), you are likely to take a lot more damage than the extra +2 you dish out.
The only, very narrow regime where this makes sense is if you know that you need exactly these +2 to force an MDS against a pretty healthy opponent.
Cat's Parry
I'm not sure about this one, has anyone ever successfully used this? You get an AoO if your opponent misses, but your opponent gets such a huge bonus to his attack he will most likely hit. IMO this is only good against mobs of much lower level than you.
Dance Aside
This one's a nice idea, as it is a passive ability and does not have any adverse effects. The only problem here is a logistical one; at least in our group whoever rolls an attack and gets an obvious miss just says "miss" and not "I rolled a 9", which would be necessary for the defender to decide if he can and does dance aside.
Decaptitating Slash
As the description reads, you usually only try this against solitary opponents. But against these this can provide a very cool and cinematic effect.
However: if it has to be actively announced this maneuver is pretty useless. Your average Crit chance is only about 10%, so 90% of the time you will just suffer a huge defense penalty without any benefit whatsoever.
Moreover, when you have BAB10+ and score a crit, you are very likely to cause Massive Damage anyway, so you don't need this maneuver at all.
In short, it's pretty, but rather useless.
Desperate Stab
This one's awesome. As should be expected at such a BAB prereq.
Devastating Sweep
Who takes Whirlwind Attack?
Distracting Arrow
Not quite bad, not quite the hit either, as most things that have to do with ranged combat.
Force Back
This one's pretty good; you lose nothing by using it. Either the defender stands his ground, then you deal the same extra damage as PA normally would, or he retreats, and takes regular damage and draws an AoO, and you don't draw AoOs by following up.
Fling Aside
Huge prereqs (4 feats!), but a cool and useful effect with no downside. One possible exploit here is that you can keep trying to knock down even really powerful opponents who would normally trip you in return.
Hooking Parry
A pretty nice maneuver that you often see in movies. If you do it right, you can take real good advantage of it. For example, your buddies can close in on your opponent and he doesn't get any AoOs.
By the way, I think the only reason why they made this work only against reach weapons is to avoid it triggering too often.
Human Shield
Also one of the great cinematic actions. Remember that by taking a -4 penalty to your Grapple roll, you can hold your victim in one hand, while using his other hand to attack normally.
Improvised Attack
Pretty cool because it's a Free Action, and also very stylish, with low prereqs and a small penalty. Note that the penalty only applies to the first attack. The second attack carries the usual penalty for improvised weapons: -4 for most characters, -2 for lowlevel Barbarians, and no penalty for Barbarians 7+.
Kip Up
Finally a good use for the Jump Skill. Unfortunately this immediate action triggers a rules collision: this maneuver reads that you get up _immediately_, and the Improved Trip feat gives you an extra attack _immediately_. Which comes first? The question is if you have the -4 Defense penalty against this followup attack.
Also, you can ignore the AoO if you have Improved Mobility, but keep in mind the 10' restriction (it's one of the unsolvable problems, but I think I'd rule that the tripped character avoids the AoO if he moved at least 10' on his previous turn).
Leaping Charge
Pretty good at the first round of combat if you catch your opponent(s) flat-footed, when they are easy to hit. Best used against solitary opponents so you don't suffer too much from the -4 Defense penalty.
Leave them for Dead
As the description says, this one's for fighting "lesser foes" that can't hurt you much even with their AoO +4 to attack.
Masterful Disarm
A nice cloak-and-dagger style add-on to Disarm with no drawback.
Pantherish Twist
Who didn't ever dream of that, making two opponents attack each other? It's a cool idea. Unfortunately, it's extremely unlikely you'll pull it off. It requires TWO opposed Dexterity checks, and each opposed ability check is terribly random, because the random element (i.e. the d20) is much bigger than the fixed element (the Dex mod).
Ranged Disarm
Reasonable tactic for Delay / Area Denial, because the opponent has to pick up his weapon again (move action) and thus cannot move and attack in the same round. But the best use for this is to have an ally closing in and attacking the opponent after he is disarmed. So when he tries to pick up his weapon he draws an AoO.
Riposte
Cool idea, but the same potential problem as Dance Aside.
Shield Slam
Again, there's the problem of the bloody random opposed ability check. Still, not a bad maneuver, as the wager is manageable. Maybe your shield gets damaged, so what?
Sundering Parry
Haven't tried it out yet, but it looks very powerful. Especially for Soldiers.
To the Hilt
Again, a nice idea, but rather weird implications. You should allow the attacker to deliberately leave the weapon stuck in his enemy if he so desires.
Note that the description says nothing about the attack having to be a melee attack, nor do you have to _use_ Power Attack with it, so nothing says you can't use this maneuver with ranged weapons. Arrows are piercing weapons too, and Axes are really most decorative when firmly lodged in an enemy's collarbone.
Keep in mind that this only works against unarmoured opponents.
