I've not noticed any comments about the staircase from the crew or passengers. I'll just say that it was pokey and commonplace. People of 1912, especially the well to do, were used to seeing far grander staircases in big stores and public buildings. When James Cameron made his flick, he had the staircase made larger than the original, because it was so narrow and ordinary.
Pokey and commonplace I don't think so. Yes rich people were used to seeing bigger and better, but this was on a ship. Just 10 years before, the first class staircases looked like the ones from 2nd class.Talk about ordinary. So this was a huge improvement.