Book bannings have always fascinated me...too often, the person offended has never read the book...or simply interpreted it the way based on his/her initial perception rather that what the book was truly about. Or, simply listened to heresay.
Anyway...
That being said, if the Harry Potter series were being written from the point of view of Voldemort or even portrayed the horrible acts in these books (i.e.--Umbridge's detention with the nasty quill, torture of people, merciless killings, etc.) as anything remotely acceptable or appropriate, then I might be able to see what the banning was all about. In actuality, the message of the books expouse just the opposite: they disdain racism, abuse, prejudice, etc. In a straightforward case of "good vs. evil", which these books are in large part, good clearly is who JKR wants us rooting for. I would think the book banners would truly appreciate that, and while there are books out there that could be deemed offensive to some (not every book is for every person), that doesn't mean every offensive bookj should be banned. Were that the case, there wouldn't be books to read!
Everyone has different values. I say, read a book first and really be objective about it BEFORE making a decision if you're in the position to decide what's appropriate for someone else (like a parent for his/her children). If you choose not to read a book at all, that's up to you...but I'd make sure I was making that decision on my own and not based on what others said. I don't think all people have to come to the same decision about all books...we all like different things, and that's a big reason why I think there are so many out there to choose from. Just because you don't care for it means that everyone else does or should feel the same way.
Just my two cents...