Disclaimer: This review may contain minor spoilers. Watch out!
I haven't seen any of Dario Argento's other films, but from looking at reviews on IMDb, it isn't hard to see that Phenomena (or Creepers, as it was retitled for its heavily edited U.S. release) was a hit or miss for fans of his other works.
So why did I decide to watch a film like this? Well anyone who knows about Phenomena's influence on the 1995 survival horror game Clock Tower ~The First Fear~ will understand why this movie piqued my interest. "A movie that is like a movie of Clock Tower? I'm there" I probably said to myself naïvely. But that's where I went wrong, because apart from some aesthetic similarities, such as the main character Jennifer looking like well erm... Jennifer from the game (see, even the first names are the same!), as well as some other minor detail similarities, Phenomena is no 'Clock Tower: The Movie' (they are actually making a Clock Tower movie, but it has been stuck in 'development hell' for some time) but a movie wonder of its own. I went in expecting some random b-movie style horror film that just so happened to be an influence on one of my all-time favourite games, but perhaps my ignorance paid off, because it meant my expectations weren't at any level and I came out having watched something that I thoroughly enjoyed.
The story of Phenomena revolves around protagonist Jennifer Corvino (played by Jennifer Connelly) who arrives at an eerie Swiss boarding school for girls. After getting into a spot of bother while sleepwalking she gets lost in the woods and is found by the chimpanzee assistant of forensic entomologist John McGregor (Donald Pleasence). McGregor witnesses that Jennifer has a special gift for telepathy with insects, and asks her to go on a journey to find a killer of girls, with the help of a fly. She uses the fly, which is drawn to decaying human flesh, to help her track down the murderer.