The most striking difference is of course the graphics. Modern HD graphics and improved animation technology made the movies look much more impressive than the series 15 years ago of course.
I watched Evangelion 1.0 first, then the series including End of Evangelion then Evangelion 2.0.
So directly coming from the first movie to the series the graphical differences pierced into my eyes. Now there are details never seen in the old version, crisp and vivid making the movies eye-candy you don't want to miss out on. It is like switching a game from minimum graphics settings to maximum.
While the first movie adapted many of the original scenes Evangelion 2.0 strayed further from the original plot. Though in a way I fully approve of. There weren't many changes with Shinji in the first movie, but in the second movie I actually liked him. Finally he's bahaving like a hero saving the earth should be.
Asuka got a little more tsundere traits which make her cuter and more amiable than her counterpart 15 years ago. And instead of letting Asuka completely turn into a psycho bitch, they introduced a new quite interesting character: Mari. Although little is know about her, I already like her :D
All in all I can't point out anything that did not improve from the 1995 anime.
But this is the first half. I also kinda liked the first half of NGE.
What I'm really curious about is how 3.0 will turn out.
In my review of NGE I already stated that in the second half, the plot and character development went downhill. Giant plotholes and Shinji's and Asuka's bitching turned the series into something I wouldn't want to do to myself another time. If 3.0 turns out to be something in the lines of ep 25/26 of NGE I'll send Anno some letter bombs +_+
