The apartment is really well located, close to Karlovo namesty (Charles square) metro station and within walking distance from the new town. It is fully equipped and furnished with a nice "bohemian" touch. There are also lots of books in English. The only drawback I can think of would be that you can't stand in the bathtub which can be annoying for tall people :)
Roman was very available before our trip, and even though we couldn't meet, it was very easy to get the keys. He also sent us an e-mail with lots of recommendations on where to eat and what to do in Prague. I'll definitely recommend this place to my friends.