We really liked the Siam Square area, and the A One Inn is a short 5 minute walk to the MBK shopping mall complex, the SkyTrain, and a short walk to the Jim Thompson House. We stayed here after Wendy House, just a couple of doors down, didn't honor our reservation and gave our room away, even though we reconfirmed less than 24 hours prior. The room at A One Inn was very basic, but it was clean. We had hot water in the AM, but not always hot in the evening. The tv only got one foreign language channel. The had wifi and computers in the lobby, but you had to pay, although the rate was reasonable. The staff were nice and friendly. The room rate was 700 baht. If you just need a place to sleep and don't need many amenities, it is a good place.

We arrived and the hotel was being renovated...which meant that we were sent to the last floor on rickety temporary metal stairs. The room was nice and brand new but street vendors start making a lot of noise early in the morning right by the hotel.
What did it for us was the staff being very rude and not believing that we did not have toilet paper in the room, we left the next day to a better hotel down the street (Pratunam house). The hotel would have been worth it if there were stairs and tiles on the floor and no sinks laying around.
The hotel is right near the MBK which makes it a great location

Having previously reviewed A-One and stayed there several times after, I must say that they rarely honor their reservations anymore. I have made several reservations (asked for a new room) and when I arrived they only had an old room. The last time I stayed there they didn't save me a new room and put me in an old twin room. When I asked why they didn't have the other room, they don't have an answer. They just gave it to someone else. I stayed when the clerk indicated that I could change the room the next day because they would have rooms available. However, the next day I was told they were booked. As a result, I checked out. Frankly, I am tired of staying here because I never know if they will have my room when I arrive and have to find somewhere else to stay.

The room is ok as hostels go but this place advertises itself as a hotel and has prices to match. The advertised satellite TV is, in reality, 3 thai channels and the staff refused to try to help with that. The bath rooms are tiny and the rooms aren't very clean. The whole place is lacking atmosphere. The main bad point is really the unfriendly, rude staff.