I enjoyed the first, which I got for free, enough to buy the second for $7, but I'm too cheap to buy any more.  I would definitely continue reading the series if I could get it for free, or only a couple of bucks each. The good guys are good, the bad are very bad, and there are some very normal people who have some good days and some problem times. The main characters are likable. The adventures fit the general mold of young people trying to save the world, or at least their part of it. Companions on a quest kind of thing. The series is oriented toward a teen audience, but that's about the level of complexity that  my mind has attained to in my sixty-eight years.