I was thinking in terms of a human or humanoid fighting other humans or humanoids, with the DDG feats. Against monsters, they aren't going to be very useful.
Against the Three Musketeers, who are super-specialized with swords, disarm and sunder would be quite useful (the same applies to one Drizzt Do'Urden, also.)
If your trying to take a foe alive, grapple is useful. If that foe has some sort of killer attack (4 attacks per round, or some nasty spell) grappling takes him out of the combat briefly, while your friends deal with his underlings.
If you're near 0 hit points, Combat Expertise keeps you alive long enough to maybe retreat from the fight?
Dodge and Mobility help against all those AOO. In a combat like the Moria combat in Fellowship of the Ring, AOO would be going off by the baker's dozen every round.
Improved Unarmed Combat means you can brawl really well. I ask: what fighter wouldn't want that, other than the paladin or cavalier, who insist on formal dueling? (Woe to said paladin or cavalier, when their foes starts fighting dirty. They might call that dishonorable and foul, but that will be small consolation when they're dead!)
Power Attack was among my DDG Feats, and everyone seems to like that one, even thought it doesn't seem to be very useful at low levels.
(Gets this humorous image of someone trying to grapple a beholder. Result? CHOMP, crunch, munch.)
(Notes that grappling Dragonlance kender is a real bad idea. Not only do you fail to accomplish anything useful, but you lose most of your items. Probably for good, too, unless you are real good with the Search and Spot skills.

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I'll head on to the other special attacks. The remaining ones being: Feint, Mounted Combat, Overrun, Sunder, Throw Splash Weapon, and Turn Undead.
Then I can understand better how your mounted fighter works by the rules, sniffles (mounted combat, ah yes ... the realm of Tolkien's Rohirrim and French calvary and the Mongol horsemen, among other notables.)