Well for one, all male voices for all the actor (puppets?), everyone sounds the same until he meets Lisa. She sounds different and and has a female voice actor by that director shows, not even with images or dialogue but with sound that she is special to him and to us. Usually in movies it's just two beautiful people and you don't get why they are together or it's just shown in some tiring, boring way, but not here, which I though was incredibly creative and a genius way to show how she is special. Also great use of stop motion, rarely a movie uses it's format, using one of few things that are specific to animated movies - voice recording in special way and making it important part of the story, for that reason alone it would be impossible to remake this movie in live action and keep all it's elements intact. All the nudity, sex scenes, all the stuff that live actors would be uncomfortable doing, we can see them and get to know them at they're most intimate moments, that's the most private way you can see someone also used to develop they're characters.
Character development for everyone and not in a forced way, everyone feels human, awkward moments that aren't in movies, mostly people are too perfect, too planned out, nothing feels out of place or weird, but here there are these moments that give this movie mare reality, awkward conversation with Lisa's friend and Lisa when Michael invites her to his room. People curse, drink, smoke, like real people do, in every movie today no one drinks or smokes except if that's part of they're character, they are just wild or rednecks so they smoke and drink and there's always attention directed at that fact, but here it's a smart man giving a lecture, these are just his habits, no need to draw attention to them. Dialogue is perfect, voice acting is prefect, everyone sounds differently, voiced by the same actor but everyone, just by dialogue, sound differently.
Michael's illusion about running away and being with his Lisa, two of them against the world, how people feel when they fall in love, just run away from everything, for one crazy moment you think you can do it but then you come back and remember that this was all just an passing moment, Lisa isn't special but just one night stand. Lisa is the same person he meets at beginning and at the end, the one he suddenly leaves.
Not pretending like character's doesn't know about not being real. Michael taking off his mouth and scratches it before, he doesn't look surprised, just puts it back on and keeps running.
Whole story feels like cheating on speed - it's like Kaufman examined the whole story behind cheating, hitting all major points and really making us look at it not just a dragged out story. Unhappy people wanting to get away form they're life's, that's why people do it, to feel something again, believe they finally found that one special, destined person meant for them.
Hell, not going by any reviews, I don't usually read them for movies like this, just ruins the movie knowing what ideas other people find in there, sorry for spoilers I guess, this is a movie that has a lot to say and show you if you are ready to listen, it's not going to force you, there won't be some crazy twists just to keep your attention.