My wife and I recently stayed at Villa Borobudur for 3 nights. It was a wonderful experience that we won't soon forget. We were upgraded to the Merababu villa (from the Merapi Jungle Room) - and oh, what an upgrade(!): we had our own living room, pool and choice of 3 bedrooms, all overlooking the valley below, featuring mountains in the distance. At different times of the day, the calls to prayer from the various nearby mosques would echo throughout the valley, while, at other times, you could sit with a cold beer or juice and listen to the afternoon rain sweep across the landscape. It was a truly magical setting.
The dedicated staff were top notch - from the cooks, wait staff and porters. Everyone was super polite, friendly and willing to do whatever was necessary to help. The driver we had for our day trips was outstanding, knowledgeable, and went well beyond the call of duty in helping out in our hike up to the Candi Sologriyo. The Indonesian food was great, and the few times we had some "off menu" special requests, they did their best to accommodate.
A couple additional points to keep in mind: we were picked up at the Yogyakarta airport by the hotel and would definitely recommend arranging a ride - it is a bit a tricky to find and located in hilly terrain. Second, while I have a mobility impairment, making navigating the grounds a bit tricky, the staff went out of their way to help. So don't let the stairs be a deterrent.
A great experience all around!