I've always looked at Dominate monster and asked... why?
Why this is spell is level 9? when you could just use Monstrous thrall that is better in any way.
They are both enchantment, compulsion, mind-affecting, one creature target, SR: yes, Save: will negates, 1 standar casting time, V,S components. Here're the differences:
1) Range:
MT is medium
DM is short
2) Duration:
MT is permanent (as it says in the description, the duration line is wrong)
DM is 1 day/lv
3) Dominate gives +2 bonus to the creature's saves when you're attempting that he does something against his nature. MT impose a penalty of -4 until he get success on a will save.
I am missing something?