I've seen the last three of the final six, as well as the remake of Solaris.
Primer is a good film, but it needs multiple viewings (ideally one after the other!). I've seen it a few times now, and I still don't understand it, possibly because my degree isn't in physics. Having said that, even the physicists I've shown it to don't understand all of it, and many of them
do have degrees (Master's degrees, and PhDs) in physics.
I didn't think much of
The Iron Giant. I'm not a fan of the book, either.
I'm in two minds with
Ghost in the Shell. As it is, the film is very good, and some of the ideas are fantastic. However, the anime series (two seasons -
Stand Alone Complex, and
S.A.C. 2nd Gig), are far superior. If you're a fan of slow, philosophical musings in a futuristic setting, then the film (and its two sequels) will suit you just fine. The anime is a lot faster, and less philosophical, but shows off more SF elements (particularly the 'net, and a lot about cyborgs - a key part of both the anime and films).
As for
Solaris, the remake was pretty naff. I've heard the original is much better.