This is a genere film, the basic concept, and the creatures themselves are quite cliched. However, the characters and action are not. The female lead is done right, she is neither a damsel in distress but her self sufficiency is not awkwardly written or overstated as it so often is by hack writers trying to be politically correct. The male lead is interesting. He is not an action hero type, but he's brave and seems somewhat genre savvy as TVtropes would put it.
In fact I could probably have just written "The main characters are not idiots." and leave it at that, it's amazing considering the genre we're dealing with. Most movies of this type have plots and situations that are entirely dependent on the main characters being complete idiots.
The plot follows the standard tropes fairly closely overall, but manages to put enough of it's own spin on the situations to actually build some tension. Which is impressive since the antagonists are 2 foot long rubber lizard puppets.
In short, if you're a fan of creature/monster horror type movies this one will probably please you quite a bit. If you're just looking for something to pass the time and don't mind a bit of gore this film will probably do. It's a bit cheesy, but it avoids most of the worst failings of the genre.