This is a real Gem.

Rating: Null/10 (5 June 2002)

Being 9 when i saw it first, this is still my all time fav. movie up to now. I think nearly everything has been said about this movie already in the other user comments.
I just can add, it combines the elements romance, comedy and science-fiction in a very well done fashion. Some people say its corny, but i don't think.
I know some other movies which feature these elements, but tend towards getting a bit corny or stupid (f.ex. Bill and Teds Excellent Adventures, which nevertheless is very funny (if its compareable at all)). And many more sci-fi themed movies of the 80's...
All in all, for me this makes up to a very sympathetic science-fiction movie, which is enjoyable many times without getting worn off.