The whole series should be called 'Deus Ex Machina' because of the ludicrously fortuitous ways that the characters move from problem to problem. Case in point from this one: needing to get into a city unseen it turns out that the old professor is an expert skydiver, that a spaceship has a set of skydiving chutes (not just the round, land-anywhere safety chutes from planes), that they are so good that they do near perfect solo jumps with no training, etc. The series just takes any elements from other genres and stories that the author thinks is cool (Fallout, Mad Max, spy novels, Sci-Fi, now dragons) without even thinking about how to fit them together coherently - or even whether it is possible.
The characters are all pretty one-dimensional and unsympathetic, with a single, leaden 'voice' that doesn't ring true for any of them (an aged professor constantly saying 'you guys', the overly-formal, stating-the-obvious dialogue from the teenage characters, etc.)
I've now read the three books that were in the omnibus edition I bought, and given that they have got progressively worse, I won't be reading anything else by the author.