Hi OP, we have family members living in that area, so have spent considerable time there over recent years. It has always struck me as a very settled mature and quiet area, with a mix of younger families (like my in-laws) and quite a high proportion of elderly residents whose families have presumably moved further out into the Dublin suburbs. It's beside UCD but seems to have relatively few students living in the actual vicinity.
Plenty of transport options. I have used both the Rock Rd and Stillorgan Rd QBC in the past to get to/from there. The latter is particularly good as you probably know. I'm guessing the Dart is walkable but haven't ever tried. Road actually doesn't seem to be a rat run as you might expect. I think a combination of the very sharp ramps, the slip road diversion, and the meandering nature of the road probably puts drivers off. Only thing I have noticed on several visits is some pretty awful parking from drivers on street at the Stillorgan end of the road. Doesn't seem so bad down at the Rock Rd. Also not sure what's happening with the Montrose hotel, it's closed at the moment.
Not sure about local primary schools, but could find out if you're interested. I know plenty of people who attended local secondary schools. Choláiste Íosagáin/Eoin is particularly popular, but there are also plenty of private secondary schools in the area too - Blackrock, Mary's, and Michael's.
My other half was keen to move to the area at one stage, but prices on that road were €1-2m, so hardly an option for us at that time. But our relatives seem very happy there.