Pros:
1) Prague is a beautiful city and this apartment is very well located. I think there was public transportation down the street but I walked everywhere.
2) I had informed Vincent prior to my arrival that I wouldn't be getting in to Prague until late at night. He was very understanding and told me it wouldn't be a problem.
3) The room is very large and well lit. One night I invited the guests into my room to hang out because it had so much room.

Heads Up:
1) When I arrived the intercom didn't work so I didn't know that Vincent's assistant was coming downstairs to let me in. I ended up walking around and looking for internet for about 5 minutes before I came back and she let me in. I didn't see her (or Vincent) again the rest of the trip (although she did bring down a drying rack when I was out).
2) Vincent doesn't live in the apartment and there are two other rooms in the unit that he rents out. The first night I was there one of the rooms had 3 people in it, and the second night the second room had 2 people. With me included, that left 1 toilet and 1 shower (located in different rooms) for 6 people.
3) The first night I was there the internet was slow but it worked. The second night I was there I think the repeater went down which meant that there was no internet anywhere in the apartment. I was able to sit in the public hallway and use the internet but the light only stayed on for 30 seconds. I emailed Vincent about the problem and he suggested that I use the hallway or go upstairs to his assistant's place and use her internet. He responded quickly but because of the lack of internet in the unit it took me a while to get it.
4) The shower head isn't attached to the wall (there appears to be a place where it used to be attached) which made showering a bit more interesting.
5) The curtains in the room were thin and let tons of light pour through in the morning. They block people from looking in, but that's about it.

Summary:
This apartment has a lot of potential. The rooms are nice and the location is great but the internet needs to be updated and maintained, the buzzer intercom needs to be fixed, the shower head needs to be mounted, heavier curtains need to be added and the unit should have a maximum capacity of 4 or at most 5. If these changes are made I think that this might be the best place to stay in Prague, until then hopefully you'll arrive with different expectations.