I was very impressed with the visuals they showed of the underground facility/lab. The makers of the filmed showed it quite a lot so I guessed they liked it too.
Now for a film made in 1971 it couldn't have been computer animation - or could it ???
Back in the days before computer graphics, film techniques were used for special effects. Transparency projection, color filtering, multiple exposures, and animation were used in the production of this and many other movies. A lot of the special effects in those days were done in the same way animated cartoons were made, frame by frame artwork. This was very labor intensive and time consuming. Now, with CGI, effects that used to take weeks using film technology can be rendered in a few hours.
CGI has had some downfalls and some good (and very good)things were made by it. The most terrible downfall of using CGI was Jaws III. The best one I know is probably Final Fantansy VII Advent Children (which I haven't seen and would love to see. (seen trailers online)). The best movie that hasn't used CG at all is The Punisher.
I'm sorry... you clearly haven't seen the original Star Wars episode IV for a LOOOOONG time if you really feel that way about the small models used for the space scenes. Sorry, but if you would watch those scenes again, you'll realize that although very exciting scenes, the lighting, shading and background was terrible - not to mention the EXTREMELY visible matte squares visible around each of the individual models.
Hey, it was great for the time, but don't pretend it was something it clearly was not... CGI has its place, and so do the old techniques - but bashing either one utterly is a foolish position.
But I still prefer models and visible mattes over CGI. I would hop at the chance to see anything done in CGI redone with models, and not the other way around.