Basically, the issue is that the class, objectively speaking, is made stronger(yes, the Power Attack change is a buff
to anyone who isn't an optimizer, since the feat is stronger at low levels of optimisation than at high, old Power Attack is a trap for anyone who didn't actually manage to get their to-hit to the right places, or failed to guess the target AC), but casters are made stronger as well, despite some spell nerfs, so subjectively they manage to become weaker.
The crux is where the changes hit, at the top end of optimization for Fighters, the vast majority of optimized builds revolve around dumping all of to-hit into Power Attack For Great Justice. Thats no longer possible.
Things that useful on it:Phalanx Soldier Alternate
I wouldn't mind having one of these guys as a cohort. Portable cover to cancel out AoOs yay.Mobile Fighter Alternate
This one gives SOME hope to Spring Attack fighting, but of course, anyone using this for real should remember this thing called Reach + AoO2H Fighter Alternate
Not a bad dip for a barbarian or even a self buffing alchemist sort. Its not like Strength is a difficult stat to whore.
The Critical feats look nice-ish, but are too random to seriously count on much, with crits going to be at best 1/4 chance of triggering without hijinks, AND a save. And then theres the retarded thing with only being able to use one of them at a time. Two if you got the mastery feat. At least the save DC is fairly high.
Manyshot changed so that its not much good for shoot-n-run anymore. Hell, its not much good for precision damage anymore either. And Greater Manyshot can't be found.
The Vital Strike chain isn't much good and is a trap unless you're tapping 3.5 material for supersizing your weapon(hello Greater Mighty Whallop), then MAYBE its worth something.
Teleport Tactician could be worth SOMETHING, if it didn't have so many prereqs.
Sidestep is handy against full attacking enemies without Reach, pity it takes 2 bad prereqs.
Power Attack can't be used to dump excess to hit into damage anymore, on the other hand it works with light weapons, and the exchange rate is more favorable. 1:2 ratio by default, 1:3 with 2H, 1:1 with off hand, is superior to old Power Attack with the exception of optimised ubercharging or the like. The average player would be more able to use it at the least. And Furious Focus basically lets you use it for free. Deadly Aim gives a ranged equivalent, which is nice to have.
Step Up is pretty useful for Reach-AoO users, stopping the 5ft step out of reach to cast trick, but theres still ways to get past that.
Stunning/Dazing Assault are effective enough, though less than they look. Not bad for stunlocking I suppose, but you need to hit AND the target needs to fail the Fort save(which isn't easily raised for DC AND is one of the better saves for monsters). Maybe if you can get a TWF full attack going and hit with all of them. But the target's probably already dead in that case.
Cleave and Great Cleave are messed with, less exploitable, but more likely to trigger.
Fundamental issue remains unchanged, You need many feats to be good at ONE way of fighting, maybe two. There are few good feats to extend a given combat style to higher levels(and those are prereq heavy). You lose out on the 3.5 feats in relatively obscure sources.
On the other hand, Archery becomes more managable(Deadly Aim after all, works on Manyshot) but less mobile(see Manyshot).
Spring Attacking/TWFing as a fighter is now less automatically fail. You're sorta locked into the Mobile Fighter though.
Shields are the same old same old, but Phalanx Fighter does let you use a reach weapon with one, which makes you a snapping turtle with a long neck. Still a turtle though, but at least you have a decent zone of control and you can do useful things like providing cover to the casters so they don't care about AoOs. More a cohort role than a party member role to be honest.
Ubercharging is dead. Stand Still is dead. This is why Fighters can't have nice things.