We stayed 3 nights in La Rocca in September 2011 after a bustling 3 days in Rome - we chose Orvieto due to its proximity to Rome for our return flights (1 hour by train) and the proximity to the main train route.
La Rocca is set in a wonderful surrounding and is very tranquil. The pool area was beautiful and that is where we spent most of our time relaxing. We didn't have a hire car so we spent 1 evening in the restaurant and the other two nights in Orvieto town - we got a cab in and back but that cost €40 return. Having said that the town was lovely and well worth it.
The restaurant at La Rocca was beautiful and the service first class however the a al carte menu was on the expensive side and limited in terms of choice. Worth visiting once at least for the experience.
The only downside to the hotel was that as its such a small and relaxed place the reception/hotel service wasn't as attentive as you may be accustomed to - you may have to track someone down if you need a drink or any assistance.
La Rocca does also offer self catering apartments which is something I would consider next time (if hiring a car) as it is fairly remote in that you can't walk to the nearest shops etc.
In summary a relaxing stay in a stunning location.
