It really is a matter of personal preference. There is a lot of good things about the cabins, and many people love them. That being said, we tryed them one year, and they were just not for our family. We hated the transportation system at Fort Wilderness--it took a long time to get anywhere. We also hated the pools--they were not of Disney resort quality.
Also, as the last poster mentioned, you are somewhat isolated from all the Disney magic, or at least we felt that way. We disliked the experience so much that we moved to another resort after three days.
It is a different experience than we have had at any other Disney resort, and it just wasn't for us, but it really is a matter of personal preferences.