We recently made a trip from Holyhead to Dublin on the Irish Ferries Dublin Swift. We had a couple of breaks on the drive from Southampton but were feeling in need of a good coffee pick-me-up by the time we had embarked. Having settled down in seats near the onboard "Cafe Lafayette", I unthinkingly assumed that (a) all the places serving hot drinks on board would essentially serve the same, and (b) if anywhere had more/better hot drinks, it would be the cafe. Big mistake on both counts!
If you travel on the Jonathan Swift and like your coffee, avoid Cafe Lafayette at all costs. The coffee tasted like burnt dirt. (It actually reminded me a of the odd occasion at work when I have made myself a cup of Senseo coffee and forgotten to put in a new pod!) Not good.
To rub salt into the wound, when disembarking the ferry we noticed that the "Temple Bar" on board was serving Costa coffee. Duly noted for future trips!