Worst in the series...
I really love Tremors. The first film is about as fun a monster film as you're liable to get. The second film, although not as good as the first, is also a lot of fun and a worthy follow-up.
I had reservations going into the third film. For starters, the box art was cheap-looking and uninspiring. It sort of reminds me of direct-to-video box art for a bad National Lampoon film. Plus, Fred Ward wasn't returning. Michael Gross is the only returning character from the first two films, but that's a good thing. The flip side is that there's always a danger when introducing new characters to such a beloved series as Tremors.
The new characters in Tremors 3 are all pretty forgettable. None are particularly memorable (with the exception of minor returning characters such as Tony Genaro as Miguel, who is good) and some are downright annoying. This is most evident with Susan Chuang's character, Jodi. I don't know if she's a good actress or not in other films, but she is absolutely terrible in this. Not once was I convinced that Jodi was reacting realistically to the situations that the story called for. At least some of the other actors seemed to be trying. She is basically the Jar-Jar Binks of this film and her performance pretty much sinks the ship. Note to director: next time, don't have your leading lady be such a grating, unlikeable wise-ass!
As for the story, it's nothing very interesting. The beginning of the film starts off with a great set piece where Burt repels a Shrieker attack at night utilizing an anti-aircraft gun. That's a great way to grab an audience's attention, but it's also a great way to disappoint an audience when nothing else in the rest of the film lives up to this level.
Speaking of the Shriekers, the creature effects are the worst in the entire series. Part of the appeal of the Tremors films is getting to watch giant rubber puppets interact with the cast. This film does use a few puppets, but their use is extremely minimal. Instead, we get truly awful computer-generated monsters that feel totally out of place in a Tremors film. In short, the CGI in Tremors 3 is piss-poor. You know what I mean if you've seen the film (and the first full body reveal of an Ass-Blaster is the proof).
The new monsters (the ass-blasters) are ridiculous. At least the Shriekers were interesting designs and they had a cool infra-red function to them. The ass blaster design is pretty weak compared to the other films' creatures. And just the idea itself - creatures that shoot fire from their rectums? This is a low point for the Tremors films. The first two films were good enough that they didn't have to rely on such an absurd and juvenile attempt at laughs and/or creativeness (and I use that word loosely, here).
The final battle in the film takes place in dark shacks where much of the action can't even be clearly seen and...
...Oh, forget it. I've already used too much space going on about Tremors 3. In short, it sucks and is the weakest of the four films. See it if you enjoy being disappointed or if it doesn't take much to entertain yourself.