About the book...
Kernel Fleck sees lights - it's one very important factor to keep in mind. He sees lights, he had control these special lights, and now, they're talking to him. He fights demons, he's part of a weapon, and the universe is at stake in the next battle. Darren Shan (the oh-so-famous author) picks it up around there.
Was it as good as the prequels?
Most definetely. I'd go as far as to say that it's perhaps the most important book so far, as it gives the reader a lot of answers as to what's going on. The series, up to then, looked a little... well, I won't say messy, but it was at the stage where it could be hard to follow. Dark Calling filled in the gaps and gave us more than we thought we'd get.
The only bad thing...
Well, there are two, but one isn't Shan's fault. It's a typing error in the back of the book. It says the final book is coming out in 2010, not 2009, and there's a line that wasn't brought down past the actual text of the book. No, the problem is that the series is coming to an end!! Hell's Heroes is the final book in the ten book series, and should wrap everything up. It's the big problem when authors tackle a series of books - they sometimes don't know how to end them. Shan had an...okay ending to The Saga, so he knows what he's doing. I expect he's going to follow the same sort of feeling the rest of the Demonata had - it's going to be a mighty big ending!!
I heartily recommend Dark Calling!!