I really liked the Harry Potter series, although I readily admit it is not literature for the ages. It’s just like in the movie industry— G-rated adventure stories can be big blockbusters. But then the makers have to try to do something more ‘grown-up’ and they go on to produce R-rated stuff that bombs.
Family entertainment will not gain you respect from snobby peers in the industry, but it will make you a ton of money if you are reasonably good at it.
IMHO, the greatest benefit of the Harry Potter series is that it gets kids to read, and to enjoy reading. They can move on from there, but something has to spark an interest in reading itself. This is especially true in an error when so many alternative options (i.e.,computer games) are availabe.
I teach a Harry Potter literature class and our local community college has asked me to teach it there as well. There is so much literary content that we can’t make it through all of it in one semester. The mythical, classical, Biblical, alchemical, etc. references are very richly done. The classic good vs. evil plot is quite intricately woven into the classical mono myth cycle. Rowling’s use of Chekhof’s gun is insane. Heck, I could teach an entire semester on just the Nazi allegory alone!