My use of ferries is mostly pre-determined by where I want to go but one aspect of the Hoek<->Harwich Stena ferry that frustrates me is their requirement you book and pay for a cabin on overnight crossings (and my onward travel means I need an overnight crossing). Brittany ferries eg Portsmouth<->Caen you just find a seat ot floor somewhere and use it to sleep on (cheaper).
OK, two aspects that frustrate me about the Hoek to Harwich crossing is that the terminal in Hoek has no cycle facilities. For a country where cyclists are so well provided for the terminal at Hoek as "disappointing". In miserable weather I've taken my bike into the terminal and been shouted at by some supervisor ... Whereas departing Harwich once got there early and security guard let me into the terminal to wait, riding my tadpole recumbent across to the coffee machines, toilets, etc.), very helpful. He did ask me to stay round by the vending machines out of sight of others as he locked the entrance door behind me.