I re-watched this last night, I remembered not liking it when it first came out, but I thought maybe I had judged it wrongly.
It's got quite a few major plot holes and the special effects havent held up well, BUT it is a good fun creature feature. I always Enjoy Justin Long and he does well in this.
It's scary enough to enjoy but tame enough that I'll watch it with my kids when they're a little older.