Shibu Onsen is a delightful place to visit and while definitely developed, there's some charming treats here and plenty to do for those who want to spend a weekend. If you can afford it, spend at least a night in Kanaguya Ryokan, an old-style building with a maze of corridors and a bunch of different kashikiriburo (private reservable baths), each one different from the next. It's also centrally located for those wanting to do Yu-meguri around the nine public baths.
You don't have to be staying at a fancy ryokan to enjoy what Shibu Onsen has to offer -- Nine delightful public baths, each with a different character, quality, and water temperature, are sprinkled around the village, and legend has it that if you collect the stamps from all nine baths you can then ask for a wish to be granted by the gods who inhabit the nearby temple. You could even see the famous "snow monkeys" there as well, as they come down from the mountains to search for food in town and to bathe in nearby Jigokudani. As far as developed onsen go, Shibu is right up there at the top -- interesting, cute, quaint, with lots to see and do. It's a great way to escape Tokyo and visitors will be glad they came here. Visitors who stay at Kanaguya Ryokan will be even gladder!