Kingmaker was very popular when it first came out, as it gave you more of a sandbox to play in vs previous adventure paths that were more linear in nature. So, I think a lot of people liked it just for that reason. However, IMHO, it has some good material, but some of the adventures I thought were kind of mediocre, and it does require a decent amount of book-keeping with the kingdom building. (When I ran it, nobody in my group wanted to do the book-keeping, so I did it as DM and just asked for PC input on important issues...) So, I think now that it's been out for a few years, it's lost a bit of its initial luster.