"We had an excellent stay at Center Hotels - Plaza! We chose an 8th floor room with our own balcony, which are all on the back side of the hotel, which helped as I know others have said the plaza facing rooms can get a lot of noise from the plaza itself as there are bars/restaurants. The room was super clean, beds were very comfortable, and the bathroom was large and really nice as well!
The only thing is that the rooms get verrrry hot during the day when the sun is shining, we would keep the curtains closed and it would still heat up a ton - luckily we would just open the balcony door and the small window and get the fan blowing and it would cool off quickly, but I could imagine in a room without a balcony door to open and only a small window it would be way too hot.
We had shared it was our honeymoon and they left us cards and some treats in the room which was really sweet of them.
Tough that there's no parking, but there is a garage nearby and lots of street parking 1-2 blocks behind the hotel which didn't end up being that bad.
The location is incredible, the restaurants in the plaza with the patios are really fun and convenient, and the whole city feels very walkable from this hotel!
We would definitely stay here again next time we are in Reykjavik!"