We visited River Valley several years ago, and to be honest hated pretty much all of it.
The ferry crossing resulted in the manufacturers plate being jemmied off the side of the van during a `security` check at Holyhead docks (replacement plate and bodywork damage paid for by the ferry company - turns out it wasn`t an isolated occurrence as some dock-side workers were selling the plates to a certain caravanning community who were using them on stolen vans). River Valley itself was fine. Large, spotlessly clean with good facilities.
Sadly the locals were a little indifferent, with the teenagers being downright hostile and threatening towards my daughter and her friend. You have to be prepared to travel as there is little locally, we went to Cork on our final full day and on getting back the site was heaving - it was a Bank Holiday and the masses of Dublin had descended upon the site - it looked like Glastonbury, only I don`t know if the people in tents at Glastonbury just unzip their tents and chuck their rubbish out onto the site before zipping up again. I felt sorry for the owners who kept such a spotless site, but their efforts were trashed in hours. It was well after midnight before the adults who were playing football decided to call it a draw and let people go to sleep.
All in all, a lovely site but pretty much in the middle of nowhere (but the pub in Avoca is worth a visit) with the hostelries within easy reach expensive for barely average food. Hated every minute of our time over there, would have left sooner if not for the ferry and haven`t returned since. Ferries are a rip-off, would now rather go to France which is much cheaper.
Each to his own - hope you enjoy it if you go.