Douglas Adams' series of Hitchhiker novels are definitely my favourite comedy stories and I thought that this TV adaptation managed the difficult task of moving it to the screen pretty well.
I know that a lot of people sneer at the rather poor 80's special effects (Zaphod's frankly absurd second head for example), but I think it really captured the book's humour, which I feel is a far more important element than the sci-fi component. In this regard, I would certainly rate it higher than the recent movie, which although I enjoyed, seemed to be missing something. Marvin is one of my favourite characters of all time and I was pleased that he came over well.
Not perfect, but still pretty good.