I stayed at Elena's place for a business trip (4 nights) in Florence. The place is very clean, safe, compact, comfortable, and practical, with an enjoyable balcony. The location is great for anyone: roughly 6-7 minutes walking distance from the train station and most piazzas, a minute away from the Ponte alla Carraia bridge to cross the Arno river into the Oltrarno district, and on the corner of Piazza Ognissanti, where you can easily find a cab any time of the day.
Elena is a Florentine herself, meaning she knows the city and its culture better than any other sources you read or hear from. She is exceptionally welcoming and helpful, and can share suggestions on authentic shops, restaurants and hidden gems.
All in all, the experience was of a lovely pocket-sized hotel: warm check-in, very knowledgeable and genuinely friendly concierge, great hospitality, great location, seamless check-out. I recommend.