Lovely hotel, but it is what it is.
Overall, we enjoyed our time at the St Anthony Riverwalk. It's a beautiful old historic hotel, and remarkably inexpensive for the neighbourhood, and good value. However, I emphasize *historic.* 
Our first impression was good walking in. The lobby and bar area are beautiful. It was probably spectacular when it was new. The staff were very helpful and friendly. 
Our room was nice, but small. I had trouble squeezing my suitcase between the foot of the bed and the TV cart, and had to put the suitcase over the bed to get it to the other side. The bathroom was beautiful, with black and white tiles and vintage fixtures. However, the bathtub was weird - kind of stained and peeling, and it sloped oddly to one side, making it tricky to stand in it. I wouldn't have wanted to take a bath in it. Also, the towels felt "historic" as well - dingy and scratchy, like bad old gym towels.
The location was great! Just a couple of blocks from the Riverwalk. I can't understand the people who said it was too far from the Riverwalk - it's less than a 5 minute walk! And super close to the Alamo as well.
An important note - the air conditioning system is also "historic." We were there the first week of March, but it was warm, and the air conditioning really doesn't cool the room. It was cooler in the hall, so we propped the door open for a while to get some cool air. I can't imagine what it's like in the summer.
There is free wifi in the lobby, but not in the hotel rooms. In the rooms it costs $10 per device, per day. However, we discovered that if we connected in the lobby, the internet continued to work in the room for free. I don't know if this was just because of our room location, or if that would work for everyone.
The St Anthony has its plusses and minuses. It's a beautiful old building, with nice staff, but it's old and kind of run down. (For example, I know that it could be very difficult to upgrade the a/c, but it's a lot easier to buy new towels.) However, it was also an inexpensive hotel, and I think it was good value for the money.