The Skyliner only serves Hollywood Studios and Epcot. Busses still serve these 2 parks, but in a reduced capacity. Before the skyliner starts running (around 7:30) those busses run about every 20 minutes. After 7:30, those busses run about every hour. Busses to Magic Kingdom and Animal Kingdom still run about every 20 minutes throughout the day.
We just stayed at Pop, and loved the ease and convenience of the Skyliner. It was so much nicer than being crammed on a bus. I would stay at Pop over the All Stars any day!