The ethical logic of the film is willing to permit a wide range of people to be Nazis, even possibly sympathetic people - a young German kid who just wants to go back to his mother; a guy flushed over the birth of his child (and his rowdy pals), and of course, Daniel Bruehl, probably the most boyishly affable German actor around, the star of Goodbye Lenin! himself. There's even a little honour in the German soldier interrogated near the start of the movie, who says he got his medals for heroism.
Alright, so Bruehl is eventually revealed to be a bastard, but otherwise the film is pushing the bounds of what it means to be a Nazi, humanizing the Nazis... and still finding it entirely satisfying to go and crush their skulls. It's actually following through the premise of films like Indiana Jones to their logical conclusion: If you are a Nazi, then against you all is permitted. Given the utter and despicable savagery of the regime there's just about nothing you can do to a Nazi that gosh darn it isn't the right thing to do.
It manages to be self-conscious but also gleefully liberated in that sadism. It even gives us the whole thing in reverse, proving Hitler is evil because he's gleefully cackling while watching Americans get slaughtered in a movie.
It also helps, mind, that I am a very strong advocate of black comedy. Killing the family man is always an excellent punchline to me, but I recognise I'm not everybody.
Sure, but the film does little to give any depth to any of the Basterds. They are caricatures, driven only by their pure and unadulterated hatred for Nazi's and Germans alike. Which is why they are no better than the Nazi's. They gleefully exterminate the Nazi's with as much relish as the Nazi's would exterminate a Jew. So how does that make them better? Yes, the film sparingly humanizes some individual Nazi soldiers, but it gives barely any character development or humanization to any of the Basterds themselves, making them hollow and vapid.
Furthermore, it would have been nice if perhaps one of the characters eventually had some type of emotional epiphany for senselessly killing so many people without a single thought or hesitation. It would have added depth and humanized some of the Basterds a bit, but no, there is no second's thought or any sign of remorse or hesitancy. They are stock standard, one-dimensional characters and they are boring and listless because of it.
Then again, it follows the norm of a Quentin Tarantino movie. Excessive violence with no regard for human life. Hell, even as a film about people kicking the crap out of Nazi's there was actually not that much Nazi killing. So it sort of failed in the one way it may have succeeded.