I started watching this mainly because it keeps getting mentioned in relation to Bliss Stage, which I'm pretty interested in right now. Last night I watched the last few episodes.
It's kind of hard to look back on, due to the fact that the different parts of the series have very different styles. The middle part, in which the action is pretty much constant and the characters are most well developed, is fantastic. Before then, it starts a little slowly. Finally, at the end, it goes into full-blown crazy psychological stuff that is fairly unclear.
Anyhow, it's a cool study of some fucked up people given terrible things that (they believe) are necessary to save humanity. The protagonist's entire story is about having the courage to do what he has to versus his desire to run away and have a normal life again. His father, a remote and hostile figure in control of the EVA robot program, has pretty much decided what needs to be done and resists any deviation from his plan (which later turns out to be diverging somewhat from the plan his bosses intend him to carry out). The other characters generally seem to include variations on these sort of stories, too.
The animation quality varies somewhat - at it's best, there are some very good sequences, but sometimes it's pretty lazy (stills montages, characters talking while their mouths are covered to save on animation, shots that just plain aren't animated that well).
It's a good one to watch, but doesn't challenge Cowboy Bebop as my favorite animated series.