I recently watched this anime a few weeks ago and decided to give it a review as no one else has done so yet; so here goes!
Yuuna and the Haunted Hot Springs is your standard harem ecchi (and when I say ecchi I mean shiz tons of naked girls), with not to much of a serious plotline. Basically, a broke high schooler psychic called Kogarashi Fuyuzora gets a cheap room in a inn, but with one catch, he has to share it with a frequently naked ghost girl called Yuuna. Then starts the 'plot' in which Kogarashi gets beaten up regularly for being a pervert around all the hot, supernatural monster chicks that live there. The main girls are moe Yuuna, whos clutsy and cute; (your basic) tsundere assassin, Sagiri; a busty, alcoholic demon who's hella flirtatous called Nonko; your classic 'legal-ish' loli inkeeper, Chitose and some others whom I'm not too bothered to mention.
Anywho, this anime is a light hearted ecchi at its core, it doesn't need too heavy a plotline, as long as you like fan-service, you'll proberly enjoy this.
Really good anime, however, the "ecchi" part of it doesn't really make sense. The only time that I saw nips was in the OVA. Other than that, there was an annoying white line covering everything. That being said, it was still a really good anime. The characters, comedy, and basically everything else was amazing!
Don't get me wrong, this anime was amazing and I had so many laughs throughout, but I feel they needed more episodes to really pick up the story line. It would have been great to see Fuyuzora interact with more spirits and to see him grow and a spirit medium, but at the same time... more about Yuuna and helping her decend should have also been implimented. Afterall, it's Yuuna and the Haunted Hot Springs. I could be wrong honestly and they might even have another season, but I feel not much was truely explained in this season.