Great collection on two loaded discs. If you haven't heard Cathedral's hard pounding, doom-like sound before, this isn't a bad place to start. If you listen and feel disappointed that their sound isn't doom-like enough for you, you probably have company. I think they get this label due in part to some of their sound but also since they've been around so long, way before some of the more classic doom bands E.G. Electric Wizard; Cathedral's vocalist can growl with the best but they tend to mix it with more straightforward singing (not a bad thing in my book).
Nonetheless, if you like the heavy rock sound at all, and don't mind it with an occasional sense of humor, you can't fail to appreciate Cathedral and their healthy output of material. If you are looking to own Cathedral's CD catalog, you would do well to seek out the Japanese releases as some of them (Caravan Beyond Redemption, Carnivale Bizarre, Supernatural Birth Machine, Endtyme) contain bonus tracks (Black Sunday, Karmacopia, Tuckers Ruck, Gargoylian) not on disc 2 of this compilation.
FYI, the Japanese edition of this CD set (TFCK-87373) does contain some extras in the form of: a sticker (repro of the cover), a postcard (in Japanese), and a Japansese insert that includes lyrics in both Japanese and English. It also has the big full-color booklet about Cathedral with explanations of the bonus material. It does not contain more tracks nor a different track listing however.