Bloodspell tells the tale of Black Canary and Zatanna's introduction as well it puts them in the middle of a deadly magic pact. I think the story is good but it doesn't have a lot of moving pieces. The simplicity for the main story allows for more side stories and world building which is a nice addition to the book. Having the girls go shopping or showing Zatanna's first day at the JLA weren't required for the book to seem complete but I'm glad they were there. I think this balance is part of Dini's mastery: too many diversions would have made the story seem without direction and too few would have showed how bare bones the main plot was. That being said I think the main story did leave me a little cold. It boiled down to pretty formulaic "trick the wizard" story telling if you took some time to think about it.
The art is cover-to-cover amazing. Quinones manages to draw Black Canary and Zatanna at a variety of ages and costumes and they always look on point. His art reminds me of Amanda Conners' but it manages to convey more depth. In a lot of cases it makes the characters appear slightly more than 2D. It's great that the story allowed him to draw as many different characters as it did.
My main problem with this book is how it's packaged. The story isn't that long but still is sold as a hard cover. The book is also one quarter "making of" material (sketches and scripts). These would have been nice to have but I think this book could have easily been softcover and missing the additional material to achieve a lower price point. It doesn't seem fair to judge the book based on this complaint but I did affect my enjoyment.
Over all I think Bloodspell is solid. I think the story is simple but there are some good moments. I think the art is fantastic. My major gripe is that $25 for a comic that you will easily finish in a single sitting seems steep. I'd wait for a sale.