Well Operation Yashima is different and so is the ending of the first movie, it was quiet shocking!
(Here's Operation Yashima in short, without the EVA scenes etc which were actually even better looking :P,[spoiler]http://de.youtube.com/watch?v=dvr7c4lQ5Oo[/spoiler]
The basic is nearly the same.. but the storie really moves into a different direction... especially @ the end of the first movie... adam is burried in the moon, and the last angel (that boy) is alrdy awake and most likely he will control eva 06 (or 05?) from what i've seen in the preview
They have a Moon base where EVA06 is currently waiting.. EVA 03 will go beserk again and 04 "dissappear" and we are going to see a prototype of EVA 05
this means -> many new characters and a new storie
but ya the first movie is BASICALLY the same till the end.
shinji fights off 3 angels like he did in the first episodes.. but the fight against Ramiel is just awesome... so much better than in the original series not only because of the animation, but because of the music and SOUNDS... god its so cool when this thing starts screaming out of pain!