How bad is it? It's one of the worse teenagers and monsters films from the 1950's.
Should you see it? Yes.
Fun fact: gila monsters defend themselves by squirting blood out of their eyes; that would've been cool to add to this film. Instead, we get the most innocent teenage hot-rodder in movie history as the hero. As people go missing, the sheriff investigates and it all comes down to a teen to save the day, after he sings a song and tries to get a French girl with a very thick accent to drink from a puddle. The monster is never back-projected, so never shares the screen with its victims and all violence is off camera. The most amazing thing about this film is the blocking of scenes - once you notice that the sheriff always puts his foot up on an object to look casual, you'll see him looking for things to put his foot on.