I saw a segment about the movie on 60-minutes. The shots they showed were some of the worst I've seen of the movie (in regards to CGI quality), but a lot of it was when they were showing shots of the art team talking about finishing touches and doing the last work on the CGI, so not sure if it was intended to be in-progress shots or what, although some of it was clearly not final as they looked more like animatics.
Either way, it wasn't the most impressive stuff I've seen (looked like new footage not in the trailers) and that might confuse people seeing the segment. It also mentioned the Abyss, Terminator, and Titanic (of course) but no mention of Aliens..