My partner and I stayed here for 1 week and loved it.
Set amidst a beautiful lemon/orange grove, the top floor B&B is in an exquisite old building. Piano itself is lovely too - there are some great little ristorantes for if the travel to Sorrento is too much (although Sorrento itself is amazing and always worth the effort), however be aware that Piano is very residential - so if that's not your thing then staying here might not be for you!
The room was huge and in keeping with the rest of the accomodation. The only drawback was that the bathroom was not ensuite and the toilet wasn't the best... Really wasn't the best - in fact one of the most temperamental pieces of plumbing I've ever encountered! However, I'm sure most people wouldn't care as much about this (my OH certainly didn't) and though the staff did offer us to switch rooms, I politely declined as the room itself was great... And I'd already unpacked...
The breakfast was tasty and sweet, served buffet-style in a pretty pink room. Again this might not suit everybody, but we enjoyed it.
All in all, wonderful welcoming staff and a lovely holiday. I'd recommend The Secret Garden to couples who are after a truly authentic, non-touristy experience, and don't mind a bit of a walk off the beaten track!
One tip: print out a map before you travel, because it truly is tucked away out of sight - it took us over an hour to find it!