I have it and it is useful, although I'm not big on book meanings; in a sense it's the ultimate LWB of modern Tarot.
It's actually a perfect compliment to Butler's
Dictionary of the Tarot, because Butler uses older sources, and Riley uses contemporary authors along with a few classics (Waite, Crowley, Wirth). A terrific book to flip through to approach a card from a new angle...
That said, if I'm researching for collated meanings, I always go to Butler first... possibly because, although there are fewer authors, it doesn't overwhelm you with conflicting opinions, and the limited pool is less overtly new-agey than Riley. Also, Butler includes descriptions and a bit more overview, while Riley's
Compendium doesn't actually identify any of the decks referenced by the assorted authors.... making it less useful and more of a hodgepodge.
I found a
TarotPassages review here and a
Villa Revak review here.
Hope that helps.
Scion