I am not the biggest fan of the live action remakes of cartoons. I was completely disappointed with the big budget version of Scooby Doo on the big screen, but was very happy with the Scooby Doo: They Mystery Begins made for TV reboot. So I went into this with high expectations as I suspect other did, and this did not live up to those lofty goals. The first was extremely well done (better as I said than the ones done with much bigger budgets), so this had big shoes to fill, and as is the case many times with sequels, it just couldn't live up to it. That being said, it wasn't as awful as some would lead you to believe either.
Despite a mediocre script and some cheesy things that I can only assume were done for budget constrains, the cast was again excellent and true in their portrayal of their characters. The standard Scooby Doo humor and homage gags are there, though not in as much abundance as the first one.
At $14.99 I think the price is a bit steep and wouldn't buy it unless you are certain you will watch it again, and even then I might consider waiting for the inevitable price drop that will happen... eventually. In the mean time, for most, the rental will be enough to just see it once, be done with it, and to be caught up when (and if) they make a third installment.