Our stay at Lucy's was fantastic. We travelled with a 7 month old and so it was very important for us to have a clean space, have really quick answers for any needs and get a quick check-in. The location was also great, the place was a quick stroll away from downtown, there were many supermarkets around and we even had a baby bed available which was very helpful.
The only thing I would mention, which of course is a particularity for our case is that the door to the apartment is a bit too narrow which meant we could not fit a stroller through the door and we had to take it in two pieces to bring it in and out of the apartment. Also, although there is an elevator, there are still quite few stairs to climb before and after getting out of the elevator. So, although there was no option to bring a sleeping baby inside without picking him up, we managed and the whole stay was great!
We highly recommend Lucy's place for a great stay in Prague!