My vote is not worth $30. I got to play it for free(and will get to run it for free) because my DM is the manager at my LGS.

Of course, I don't think it's worth owning the core 3.5 books because the SRD is online. I'll probably stay the same about 4e because the books will eventually be online. We shall see.

But even if you are the type to pay $90 for the complete core set, I'm not sure KotS is worth it. The next modules might be, but not if they stay the same quality and price as this