I stayed in Dublin Hostelling International for one night two years ago and was quite happy with it.
The standard is OK, very clean and well-kept and the interior is almost like a good budget hotel.
The staff were friendly and professional and the location was good next to the river and within walking distance to everything.

http://www.hostels.com/en/availabili...stelNumber.289

Others seem to have given this hostel good ratings as well if you check the reviews on the webpage.