The room is perfectly adequate for a comfortable stay in a very good Prague location - only 5-10 minutes walk from the heart of the Old Town, and around 25 minutes walk from the main train station - I didn't need to use public transport at all. There are 2 supermarkets very close, as well as a good currency exchange office - don't change money if you don't have to before getting here.
The room was clean and large.
Vincent met me and provided enough information to make my stay in Prague worthwhile; there are also guide books available.
Vincent was also available regularly to answer all of my questions.
As others have noted, it may not be obvious from the ad, but you will be sharing the apartment with others in 2 rooms - so there could easily be 5-6 people sharing a single bathroom and kitchen; it is a bit like a small hostel with private bedrooms. The Wi-Fi can be patchy, but Vincent changed my room to one with better reception.
Overall, this place is good value for money.