I'll preface this by saying I haven't seen it in several years, so if I watched it tomorrow I may completely
agree with you. As of today, though, I think it is a very good movie. And one of the things that makes it good is how your perception of it changes as you are in different stages of life or experience.
When I first saw it as a teenager, I saw it as a super fun story about a real cool guy. When I saw it as an adult, my view of Ferris was very different. Not that he was a "bad" guy, but that he was at the top of his life. It was all downhill from here. And I also saw the focus shift from Ferris to Cameron.
I like Hughes' description of my favorite scene in the movie, as they visit the Art Institute
I will also admit that I grew up in the Chicago northern suburbs (very close to where Hughes grew up) in the 80s, so I was the absolute prime target for this movie.