Caerphilly is okay and as a commuter location into Cardiff the trains are fine (albeit sometimes crowded at peak times, although having spent hours of my life on the Tube I rarely complain). A couple of okay places to eat and drink, like RJK says it could be a lot better likewise it could be much worse. I live in the Energlyn part and it's nice and quiet but I can be at Energlyn / Churchill Park station in 15 minutes on foot and roughly 20 minutes into town from thereon in.