After the unsatisfactory ending of the 26 episode anime, the first film Death & Rebirth provided a recap and the promise of a new ending. The End of Evangelion isn't an alternate ending as such, but more like it expands upon the original and keeping the themes and tone similar. Of course, there are changes and whether they are for the better is hard to say. The film starts off with plenty of action and feels somewhat normal. After the last Angel had been defeated, there is no need for Nerv anymore and the headquarters is under attack. It is quite cruel and horrible at what happens since the attackers kill everyone in sight, regardless of whether they were armed or not. That section forms the alternate 25th episode. The alternate 26th episode is where things get weird. It is less coherent than one would like on their first viewing, although not to the degree of the original ending. Shinji is really unlikable in this film, he has regressed back to just wanting to run away from everything, and yet he is one of the most important characters and core to several plans. The ending is a mash of imagery that keeps bombarding you with visual effects, whether it makes sense or not. After the film finishes, you'll probably have to sit back and think through what happened, and to try and process it all (in addition to probably reading a plot summary). The End of Evangelion is definitely a better ending than the TV version, but it still feels like there is no way a happy ending could really occur, and no way a relatively "normal" ending can either.