A few points that might be better:
Although this is the best remix of Still Alive I've seen out there, there are bits that I think could be improved.
1) The voice - what did you use to make this voice? Ellen McLain's original voice acting had a lot of emotion behind it, and pitching it this high kind of makes it sound a bit silly - (see the "ha ha". It doesn't carry the weight it did originally), although I understand this is a piece of music and thus you don't particularly need the seriousness. Still I'd advise using some kind of editor like Melodyne to make it sound a little less ... chipmunky? (is that the right word?)
2) Not sure I liked the pitch change near the end (1:50, "and believe me...") because it contrasted the slightly lower key "still alive" that happened right before.
Other than that, awesome remix. I feel better that I have lived and listened than I would have had I not. Really, all my criticisms are pretty much only because I love Portal waaaaaaaay too much =.='''
If my points were corrected, 10. As it is I'm going to give a 10 anyway because IT'S PORTAL. ^_^