I thought it sucked..
Basically, Darth Vader (that's right, evil death star building Darth Fricking Vader) is basically a giant whiny b*tch. He essentially spends the whole film throwing a fit until he gets his ass kicked and has to be put together, where he unbelievably WHINES SOME MORE.
Lucas simply failed to motivate the level of evil required. He wasn't crazy... so there goes the Hitler style evil. It had something to do with lack of respect and fear of Padme dying.. and a lot of whining.
Going into any more detail requires spoilers.. so I'll stop now.