The RahXephon movie didn't attempt to explain anything, it was a sort of 'alternate story'. A lot of the scenes that were the same in the movie do seem like they were taken straight out of the show, which I was disappointed in at first as well. I think the Japanese-only PS2 game even takes a different spin on the story.
RahXephon is not a show that you can fully grasp and enjoy by casually watching. You have to switch on and notice the little details that will explain most things (if not everything). I don't understand how folks can say that it's a 'mess', perhaps some elaboration will enlighten me. The ending wasn't nonsensical, it makes sense if you've followed the story closely enough.
From the general tone of my experience with Evangelion, it seems quite a bit depressing as a whole. They kept talking about how humanity is so pathetic or whatever, got on my NERVs a bit. Eva from what I've seen was definitely more of a psychology and philosophy lecture than a piece of entertainment. It's something you also have to pay close attention to in order to grasp fully, but it's very different from RahXephon in that manner.
If there's stuff about RahXephon you don't get, I wouldn't mind answering questions as best as I can.
