I stayed at Paradiso 4 for two nights with my brother-- one night was New Year's Eve. Paula, the owner/manager was so kind, hospitable, and generous. She waited for us when we arrived later than expected and gave us information about where to go/eat in the city. She prepared lovely breakfast spreads and explained with enthusiasm about the locally sourced and organic products (which were delicious, including her homemade chutney!).
The B&B was clean, bright and cheerful, in a great location in Siena that is easy to find and get back to at any hour. We did share a bathroom with other guests, and it worked out fine. I highly recommend a stay at Paradiso 4!