I'm not going to rehash the fairly well known the plot. The other reviews have already covered that pretty well. The story is gripping and the acting is exemplary. The special effects were done on a shoe string budget and show it, but still pull it off marginally (if you suspend your disbelief a bit).
So why the five stars? The DVD film-to-video transfer was made from pristine source materials resulting in a viewing experience I've not had with this movie since I saw it's theatrical release in 1958. Presented in its original 1.66:1 widescreen aspect ratio, it offers a completely restored version totally lacking any scratches or bad cuts. In addition, this version is the European edition with the main title reading "The Trollenberg Terror". The sound is still mono, but the fidelity is rather good. Nice crisp highs, good bass response, and no hiss.
Even with extra material consisting of just the trailer, this DVD is well worth it. Especially to a fan of the film. I also found the liner notes to be emtertaining and very interesting. They include a lot of backgroud to the film, the genre, and I was especially amused at an anecdote about Forrest Tucker.
If you're a fan of the film (or not), I recommend this DVD release.