oddly enough Alan your right on the mark with the script and acting, however, this movie was meant to be a tribute to the B movies of the 50s and 60s.
The marketing for this side of it was very poor so because people didn't realise this they, as you said, commented on the poor, scilly and embarrassing script. If the marketing from the studio at the time had been better dealt with the audience would then have understood, there is a lot in there paying contribution to the old sci-fis. The one that stands out is when Jeff Goldblum switches his laptop on and it says, "Good morning Dave" which is obviously the 2001 space odyssey tribute. Its hard to believe this film was at the time of its release, the highest grossing movie ever. (its now 56th).
The embarrassment is how Hollywood once again lets America save the world, and as usual makes the British look like total twats with the ridiculous upper class accent that no in this country ever uses.
Ever notice also how baddies in Hollywood films are always played by British Actors?
EG, Alan Rickman, Die Hard, Ian Holm the robot gone mad in Alien, Anthony Hopkins Silence of the Lambs, (played with perfection), Alfred Molina Dr Otto Octivas in Spider man 2, Jeremy Irons in one of the Die Hard Films as well as scar in the Lion King, Gary Oldman, many Hollywood baddies, Ralph Fiennes the loony Nazi in Shindlers List,
Are we not the best actors?
As for independents, great special effects, lousy and embarrassing script and corny acting from some of the biggest names. When this was released on 8 i was very surprised given the length, it was going to cost a small fortune back then.