I also just read the first Harry Potter book a few years ago and was very unimpressed. I was a pretty big reader when i was like 8-13, and liked the fantasy genre, so I read a ton of series that were similar to them. Plenty of serious ones, and plenty of humorous ones that poked fun of it's own genre already, and everything in between. I really don't see what's so great about it, and I have to wonder if it was just brilliant marketing and just a chain of random, fortuitous events that led to its success. Studying why it became successful is likely much more important than any writing tips or styles you could get from the books themselves.