The second novel in the series took a bit more time to get going, but, having finished it, I can see how it all ties together. If you're finding the middle a little slow going, slog through it because it'll be worth it.
It was interesting to read he had based this series on a challenge - a writing-mate said he couldn't make a good story out of a lame idea and he made one out of two - lost Roman legion and Pokemon. Heh. This book has a bit less magic than the first, but maybe that's because the concept no longer needs to be explained.
I was pleased to note there wasn't too much time spent catching the reader up from the events of the first story.
I highly recommend this book and will read the rest of the series as fast as the library can deliver it.