Honestly, i didn't get what all the excitement about Sapporo beer was about. It was ok, not horrible, but it didn't make me want to leap from my seat and proclaim it to the gods like most people seemed to tell me. Honestly, I wasn't overly impressed with Japanese beer, it was all rather light and fizzy and watery and I'm used to Real Ale. Asahi black was on the good end of the spectrum but it still was a bit like a larger with an ambition to be stout and a dye-job.
I did have a really good local brew though that was light and yet really flavorsome. No name, just a namabiru. There was a canned one too (i forget the name, it was half yellow, half white) that I got from a vending machine and was surprisingly palatable. I will still happily drink Asahi super-dry, but for me it's like... a step up from Corona which is a step up from ~really~ shit beer. Bud, for example or anything with 'light' on the label. Anything with it's own sports event.
Japanese Guinness is a travesty and should never be drunk ever, ever, ever. I DO recommend though, the international beer house in Kobe which had an utterly FANTASTIC selection, including radieuse and black varieties of Belgian brewed Leffe (excellent stuff even in the cheaper blonde and brun varieties) the latter of which was about 1000 yen for a pint, but oh god... so worth it. Best pint I have ever drunk anywhere, ever, which is a shame as i've never found it anywhere else so I'm not sure the black is even made any more.