Webern and Boulez are your guys for that. It's so different.
I'm happy! That's what I was going for. Listen to the original movement if you have time "Nacht" by Schoenberg, and spot similarities and differences.
I'm not sure if it would be justified to review these as if they were pieces meant to stand on their own. My understanding is that their just little experimental sketches of ideas. I think they're interesting ideas that could be used for something else. Even if they aren't used again, I think it's often good to play with small ideas, to stimulate creativity.
The second was my favorite, I think. I enjoyed the first one, but because it was basically canonic I found it a little less interesting. The third and fourth didn't really leave much of a strong impression on me.