Here is an interesting article from the Guardian about the film's enduring appeal. Unfortunately, it seems that this unassuming movie has even attracted attention from the artsy crowd. Well, I'm sorry to hear that, Felix.
I don't read The Guardian, by the way. Somebody sent me this link.
I found the following paragraph especially interesting, since the absence of any clusmy explanation of Phil's situation and the strange timelessness of the film are both important parts of its charm. (Actually, though I say "timeless", I always think the film has an eighties feel about, despite being made in the nineties.)
[Danny] Rubin was urged to write a Gypsy-curse scene explaining the loop, which Ramis wisely never shot. The mystery has only fortified the film's magic. Its chances of longevity were helped too by a purge on period references. Rubin urged Ramis, with whom he shares a writing credit, to expunge any nods to the 1990s: "You've gotta take all this out," he said, "because this movie is really going to go on for years and years." Compare this with Judd Apatow's films, which are peppered with gags about early-21st century celebrity culture. Parts of Funny People and This Is 40 will be incomprehensible in 50 years' time, whereas our descendants in 2063 will have no trouble understanding Groundhog Day when they download it on to their frontal lobes.
On another topic, I would like to thank everybody who prayed for my father, and ask you to please keep him in your prayers. He is having tests today.