I may be only a lowly level 30, but so far my only problem with the Dwarven Defender is the following:
Defensive Weave does not work if your high AC is too high and the enemies can't hit you.
I was against the final Bog Hag in the Blood Coven yesterday and, to defeat her, I had to remove equipment and lower my AC, so she could hit me and strike her back with the Defensive Weave.
Isn't it silly that one of your maneuvers becomes stronger as you remove equipment? And it becomes worse if you combine it with another of your class ability? (Defensive Stance)
The dwarven defender also gets innate bonuses to shield and natural AC via CON and STR, this sends contradicting a message: Is the dwarven defender supposes to have high AC or not?
My suggestion would be to decide what is it gonna be:
1) Is the Dwarven Defender a low AC class? If yes, then rework the STR and CON AC bonuses into resistances and immunities, elemental as well, since just physical wouldn't cut it in the long run.
2) Is the Dwarven Defender a high AC class? If yes, then rework Defensive Weave to make sure it works regardless of your AC.
That's all I can think of right now, my two cents. Then I'm sure that at the higher levels there could be other issues, but this is what I observed so far.