I've lived in Mulhuddart for 11 years. I live in Muhuddart Wood, in the village, (the court is in my estate). It's a nice quiet estate although we've had our moments in the past. My husband grew up in Dromheath and his mother still lives there and has for 25 years. She lives at the start of the estate, just across from the church and it's pretty quiet where where she is. Some of her neighbours are old timers too and are the salt of the earth. But you could be unlucky. Personally I would not like to live up there myself. The estates round Mulhuddart village are all pretty nice and quiet and there is lots of building going on now, mostly appartments. It's greatly improved since we've been here.
Tyrellstown is very nice. I have several friends who live up there and if you drive it's great. The buses aren't that good though.