After reading all the reviews here, I was expecting better. Rooms are ok, but the walls are so thin that if you happen to have noisy people next door like I did, you'll basically hear everything they say.
Location is just fine as there are no shops or café around.
The best part of this hotel is the restaurant.
If you're on a budget and don't mind "paper" walls, this place will do just fine. But if u can spend a bit more, probably it's better looking elsewhere.

I have visited Prague 3 times now, my husband a few times more, and we always stay at this hotel. It's a bit out of the city centre, but only a 20 minutes scenic walk along the river. The quality offered for the price you're paying is supurb. The hotel has a bar and restaurant where they serve very nice, traditional Czeck food for a very reasonable price. Recommend to anyone.

We stayed at the hotel U Semika with my wife on March.
The positive first impressions started with the exchanged e-mails, the willingness to serviceof the staff was excellent.
The impressions continued during our staying at the hotel. Very courteous and helpful staff! Extra mention for the restaurant/breakfast staff, never seen such friendly and professional waitresses in any Prague hotel!
The room was quite small but spotless and comfortable. The pillows weren´t the best ones.
The biggest negative issue perhaps on our stay was that cleaning ladies and other staff started to make loud conversations and hoovering at approx. 8 o´clock in the morning every day (our room was on the reception floor)! We would have liked to get some rest after the breakfast on some days but it was impossible because of the noise.
The location is quiet and safe very close to beatiful Vysehrad area. It is 10 minutes tram ride from the Old Town, so it isn´t in the most touristy area. This might be either negative or positive aspect depending on your wishes and needs.
There isn´t an AC in the room so in the summer months this might be an issue.

Nevertheless this hotel offers very good value for your money. I would recommend it to anyone travelling to Prague.

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. :)