Hmm.....
When I went there in 2001 I was let down.... I think, if you're interested in onsen, there are MUCH better places to go. I don't like big resort towns in Japan, such as Beppu or Shirahama. Too expensive and too crowded. I've managed to find much better places off the map. It just takes time to find em.'
(Forget Shirahama, Minabe had great centos and onsen!)