I thought it was great. I arrived in Irun a little before 7am, got off the bus (it drops people off at the train station) and immediately saw a yellow arrow right in front of me. Within 10 minutes I was at the albergue where the hospitalera set me up with a credencial and coffee. Very convenient.
I'm sure you can take the train, but it will almost certainly require connections.
2002 CF: 2004 from Paris: 2006 VF: 2007 CF: 2009 Aragones, Ingles, Finisterre: 2011 X 2 on CF: 2013 'Caracoles': 2014 CF and Ingles 'Caracoles":2015 Logrono-Burgos (Hospitalero San Anton): 2016 La Douay to Aosta/San Gimignano to Rome: