I have a min-maxed Dwarf Fighter.
Combat Reflexes and Improved Trip ... I gave him okay dex and okay STR. He weilds a Halberd and uses a Dwarven WarAxe for backup.
It's really pretty nasty. I trip, am almost impossible to trip in turn, and have a high-damage exotic weapon as a "back up" in case the halberd is sundered or I somehow lose with a trip attack. He's currently 2nd level and absolutely destroying Kobolds.
I don't think it's really overpowered at all. He IS pretty mean, though. I'd like to move him to Dwarven Defender. My usual tactic of choice is "let them come to me" ... three of them get tripped and tagged. 5-step back, rinse, repeat.
What's REALLY overpowered in 3E is ranged weapons. Especially at low levels. In the low level games I'm running and playing in so far the characters with the highest "body count" are all Rogues with Point Blank Shot. Untill level 4 or 5 I imagine they'll continue to shine from the back ranks. With minis and tactics its really obvious that cover/range make all the difference. Unless everybody enters a surprise round 5 feet from eachother the ranged combatants have an upper hand. Even with multiple attacks from melee characters, that's only applicable more or less standing still.
On the whole, the changes aren't THAT bad. Most of them are flavor. Good flavor, yes, but nothing that really throws the game out of balance. By the time a ground troop stops being overshadowed by archers those benifits are null anyway.
Half-Orc does need some goodie, though. Some skill bonuses of some sort, maybe.
--fje