I have 18k items in my iTunes library on an external drive, and after selecting File -> Move iTunes Covers to Files, CoverScout happily displayed all of my artwork. (I don't have any custom tags so it doesn't really matter if the resulting tags are v1 or whatever). Since then I've been using it to hunt down my missing artwork and it's done a perfectly fine job for me so far. I'm doing it manually over a number of sessions, and at the moment I'm happy with it. Since I already had MacJournal and RapidWeaver, CS was a heavy reason for buying the bundle, and it's certainly been worth the price.
That said about the app, their registration policy is admittedly ridiculous. I gave them a clearly fake address when they inappropriately asked for it, and the necessity of making a useless login to their site so you can attach your code to your login, so the app can access your login to activate itself...that's like, "What?" We use Macs; elegance please! I've also told Little Snitch to stop CS from contacting the mothership at launch, but obviously I have to allow it net access in general, so I don't really know which LS rule is taking priority. The other issues brought up in this thread are also legitimate complaints: installing SongGenie without an opt-in and such.
And it won't be long before I delete the rather excessive 5.45 GB "iTunes Covers" folder in CoverScout's Application Support folder, but that can wait until I've finished the first pass through my library.
It seems to be a pretty good app, hobbled by a protection/registration scheme that makes the company look pretty bad. But it was cheap, so I'm happy.