Haven't stayed at the Fairfield, but we stayed at the Courtyard by Marriot in the same complex. It is a gaited complex with a nice food court and arcade. Fairfield has a free continental breakfast which Courtyard does not. The complex is fairly new and very clean.
The Courtyard has a great indoor/outdoor pool with a waterfall that you can swim through. The outdoor side of the pool has a zero entry which is nice for little ones. There are two hot tubs - one inside and one outside. As a Fairfield guest you can use the pool at Courtyard.
We didn't use the busses, but they come often - didn't hear of any complaints.
We really liked this area and had no trouble at all driving to the parks and as previously posted, it is very close to Downtown Disney and area restaurants.
If going to Universal - the traffic does backup. We noticed heavy traffic on the road to the outlet mall as well (may have been due to Saturday night mass at the Catholic church).
We would definately stay hear again (especially since we got it for $25/night)