I should clarify that there are two kinds of bottled Guinness. The old-school kind with the yellow label -- the so-called "Extra Stout" -- is terrible. Its only legitimate use is for cooking. At least five times I've shown up as a guest at someone's house and had them beamingly present me with a six-pack of it because they're trying to be good hosts and they know I drink Guinness. I smile and grit my teeth and get through a couple bottles.
The "new" bottles -- the ones that claim to be "draught" and have the widget in them -- aren't terrible but I still don't drink them except in some extreme circumstance.