Fortune smiled on me as my wife was make a Guinness & Chocolate cake (yup, as good as it sounds...mmmmmm) and so there were a few left over from the 4 pack of bottled Guinness.
Wow. This stuff is great. Different, I assume, to draft of canned, but so dark and tasty. Very 'porter' like, but more of a slow caramel burn. No fix - as flat as a pancake - but the depth of flavour makes up for any lost texture.
I'm converted.