Idan's flat was a great place to stay during my 3 days in Prague — just a few minutes walk from the old town square. It is possible to see the major tourist sites without using any transportation at all.
The apartment is clean and well-maintained, with a bathtub suitable for a long hot soak after a rainy day (it rained every day I was there). There's even a Nespresso machine to help shake off a night of Pilsner and Becherovka. The building itself is a bit dreary, but you're not going to spend any time hanging out in the stairwell, I hope.
Idan was a friendly and helpful host. He provided a map and useful information about less-touristy areas and restaurants. He was available by SMS and was even flexible with my check out time.
As others mentioned, there is construction/archeological excavation work across the street. The work starts at 8:00, but the workers show up at 7:30, so it was difficult to sleep after that time. It worked well for me, though, as it functioned as an alarm clock and helped me get over my jet lag (and numerous hangovers).