My sons and I are big fans...we are on the 2nd one now since they are hard to find in our library system. Sure, they aren't literary masterpieces, but they are wildly adventurous and entertaining. They appeal to boys as well as girls, which most book series don't.
In addition, there is a web site that has an interactive game plus forums, video games, etc. My kids were ecstatic to find it. They wanted to meet Ridley Pearson but it didn't work out. Apparently they are doing a Kingdom Keepers scavenger hunt type thing but only for big groups and schools in Florida...?
I definitely think your son will like the books, but they are a little creepy. My youngest held onto my arm a few times, but good triumphs and that's the main thing.
I personally didn't get any negative vibe about the CMs...well the ones who were human. I also don't see a negative slant put on Maybeck...the opposite. He's the cool guy, whereas Philby is the nerd and Finn is the "hero".
The books are not much more than entertainment and a way to live the Disney Magic at home while expanding Disney's audience. If you think about it, the major audience of the parks is pretty young. These are aimed at a young adult audience to make the parks still cool and hip instead of "just for little kids". Smart move, overall.