Really? I spent a few nights in a capsule hotel in Shinjuku (Tokyo) and the experience was great. It was cheap, quiet, clean, and had everything I wanted (quiet private space, free coffee and "onsen" bath. Would definitely recommend.
Never stayed in one, but "quiet and clean" are pretty much de facto standard for any Japanese accommodation.
I always enjoyed their hotels, and my preference was usually some of the cheaper ones, like the Prince hotels. I have stayed in ones like the fancy Dai Ichi ones, but I felt that they weren't really all that much better than the cheaper ones (but I'm sure there's even fancier ones, for folks that can afford).
