I used to live there, it is really quiet and not much in the way of facilities ie restaurants or theatre, social life etc, but I presume you are going for a very quiet life, and you will get it there.
I'm originally from Bekan but own a house now in Claremorris although I live and work in Dublin. I'm home some weekends so I've seen that them houses are being built there in Greenwood. You definitely will need your own transport although the Pub/Shop/Post Office is within 15 - 20 minutes walk. Knock is approximately 3 miles away but it's not exactly a metropolis. Ballyhaunis is approximately 4 miles and Claremorris is 7. Any other specific information you need or any questions you may have, feel free to PM me.
This is a lovely location but yes quiet - you will defo need your own mode of transport. I am from Claremorris which isnt far - all of this area of the county is starting to get built up but I dont think its got as far as Greenwoods quite yet!