I haven't stayed at the campground but I've walked through it to get to the ferry. I would rate it as a nice camping area, but not really the comfort or service level you would normally receive from Disney. If you really like camping and are trying to cut costs, it's a very viable option. Some cabin sites are going to be a bit of a hike or even bus ride to the ferry boat, but others are quite an easy stroll. I think they run ferries to only Magic Kingdom, so that's the way to go when visiting that park. Epcot, Hollywood Studios, and Animal Kingdom either require a bus or multiple stops.
Are you pre-purchasing tickets from your px or base ticket office? We found the savings on ticket prices that way to be significant, but it might limit your choices for what to buy.