Silverwing was one of my absolute favorite books when I was in my earlier teens!
I kinda found that the second and third book just didn't quite live up to the promise of the first, although they were quite good in their own right. Personally, I thought they crossed the line into out and out magic and mysticism, whereas the first book was set in a relatively real world. Well, except for the talking bats, but the book left me really wondering about any bats I saw from that point on
What I liked most about
Silverwing was how Oppel managed to build a society of bats, complete with it's own myths and traditions. I thought that the soundmaps and the use of sound for illusions were too cool, and the whole 'mystery' of the bands was pretty interesting too. I should really reread
Silverwing at some point, right now it's just gathering dust on my bookshelf..