It's a pretty big deal in the St. Paul school district. It's very competitive to get into one of the programs in the district, and--at least in Minnesota--it's definitely considered more prestigious than AP. That's because any high school can offer AP, but only select schools offer IB. Of course, I also didn't realize that there was an international organization that certifies the IB programs until I looked up the web page of our local high school. Anyway, here's the IB Web site: http://www.ibo.org/ibo/index.cfm
http://web1.ibo.org.uk/gallery/index.cfm The art gallery from our exams is the best part of the entire site. EDIT: IBO is the work of the devil. The entire organization can die a slow painful death and it wouldn't make me very sad. That said, I really do recommend it to everyone.
I took 10 AP tests. The only advantage was being able to register earlier than most because of all the credit I got. Personally, I feel that they did not prepare me well for college work. I took one test cold, with no prep for it (my rich-ass private school paid for all of them) and aced it, but I still fell on my face on that subject in college. For core classes, take the credit. But for courses required by your major, I say at least try some of the intro stuff.
It's only the first week of school, but my AP US history class is great. The first time I've actually seen open debate (with numerous participants) in a classroom.