I do not own or carry one myself, but I have used them before and know a couple people who carry them. When I have used one, it seemed solid and sharp, and was lightweight.
Looking at the Spyderco website, the knife is made of good steel (8CR13MOV), and only weighs 4oz. What isn't to like? It is a solid knife and it can be had for a great price.
If I had to come up with a complaint from my (admittedly limited) use, I would say that the knife seemed a little bit thin - it didn't really fill my hand as well as the Griptilian that I usually carry, but I certainly don't think that should prevent you from buying one.