We went to Prague for the New Years Eve celebration. We stayed in the U Semika hotel, because we found it ok from several points of view - price, location, good reviews on this website. Everything was very nice- the staff (mainly the hotel manager, a very helpful young girl, and 2 girls from the restaurant) were very helpful indeed. After reading the reviews on tripadvisor.com, I decided to ask for a room on the top floor. Be careful! Don't ask this kind of room during the winter time, because there is at least 1 external wall and the ceiling. Our room have not been used for some days and when we got in, we instantly start shaking. It was incredibly cold, considering that ouside there were -12 C degrees. I went to the reception and asked for an extra heater(we have already started the one in the room but it was not enough). We received another one and all availability from the hotel manager to change the room if that won't do. In few hours the temperature in the room increased and we decided not to change the room any more. But this was a mistake, because the bed was not actually a proper bed. There was a kind of esplanada on the floor and over that part the matress was placed, surrounded by a wooden frame. That frame was higher than the matress and we hit all the time by our legs- we got some bruises from that and from the pillar in the middle of the room, next to the bed :)
My suggestion would be - avoid room no.502 because it is clean and confortable, on the whole, but I had a problem with this improvised bed :)
Otherwise, I recommend this hotel to everybody and also the food in the restaurant - it is very good and, indeed, you get 20% discount, even if you drink only a beer. I would also mention the cosy atmosphere and scenery.
I really consider this hotel&restaurant as nice and cosy

PS I am really sorry I didn't accept the hotel manager's proposal of changing the room. If so, I would not be complaining of anything now. :)