P J Murphy's Irish Pub is well-located but easy to miss. It's right on Nathan Road in the very heart of the Tsim Sha Tsui tourist zone, but its entrance is just a doorway wide, leading down into the pub in the basement. Irish beers and ales predominate, and the atmosphere is kitschy but relaxed.
Murphy's details are:
Basement of the Imperial Hotel, 32 Nathan Road, Tsim Sha Tsui
Phone 2782 3383