It's a pretty decent place for Prague. I've seen worse and paid more.
Pros: you walk 5 minutes and then take the tram to the city center; quiet area; good bed; balcony; basic amenities are functional.
Cons: a bit err on the cleanliness in some places - balcony, walls; paint on the shower ceiling was falling; things like hair dryer and ironing board are at the reception.
So if it's for a city break and only need a bed and a shower, it's a pretty fine place. If it's for more than two or three nights, then I would recommend something more comfortable.
I would recommend this for solo travelers who like to backpack and just go around places.