My mother's friend lived there many years ago - they were known as "flats" then! - and I visited many times as a child. It didn't seem terribly small to me though apart from the kitchen, which was tiny.
The layout seems to have changed since, bedroom 2 was the sitting room, and the kitchen/dining was the bathroom (long and narrow on the left as you went in) and (separate, obviously!) kitchen. What is the sitting room now was bedroom 2, and where the bathroom is now was part sitting room, part bedroom. Bedroom 1 seems to be a little bigger than the sitting room, maybe it could work a bit better if they were switched around? I seem to remember everyone had their own little "coalshed" outside, I don't know if that's still the case.
The area is fantastic, shops and restaurants all over the place, walk to Dalkey, Glasthule or Dun Laoghaire. Dart & buses a short walk away, sea a stone's throw away. Yet it's not built up too much, there is a feeling of openness and green space in the area. I'd love to live around there.