I had seen the London Porter in drinkstore a number of times but I recently made the decision to try it for; eh... research purposes.
In theoretical terms, a canned beer should not only be just as good as its bottled counterpart, it should actually be better. Draft beer is not served from big glass carboys, it's served from a stainless steel, or sometimes aluminium keg. The Aluminium ones tend to have a lining inside them to keep the beer away from the metal and that is usually the case with canned beer as well. If you think there is a metallic taste off canned beer, stop knacker drinking it from the can and pour it into a glass like a civilised person. Since it's a can, there is zero potential for light to interact with the beer. Apart from shipping and weight advantages, you can actually bring this to a beer festival.
London porter is a beautiful beer in bottle, on cask it might bring a tear to your eye as it's perfection in liquid form. I am happy to report that the same is true for the canned product. No fancy nitrogen widgets in this and none is needed. If anything, it is quite possible that the canned version is better than the bottled version, but that's only because it's fresh in my mind. I would be curious to try them side by side in a blind taste test. The espresso and milk chocolate off this beer is just astounding. I have had milk stouts that taste less milky than this does.
It's time to get over our canned beer snobbery methinks.