I ran our group through it, and we enjoyed it quite a bit. The CR broke down a little after the players had leveled up to 2nd, so I threw some extra monsters in. It got better after the critters figured out they were being invaded, and grouped together in large groups as compared to the smaller groups they are designed as. At one point, the party barbarian ended up as a pincushin...all in all, we liked it just fine.