It looks nice, but I kind of feel it misses the point (at least for people like me). I like the information-dense nature of HN, adding in a bunch more whitespace reduces this advantage. There are improvements that can be made to HN (such as being able to collapse comment trees that are obviously descending into pointless bikeshedding), but improving HN by reducing one of it's key advantages is not what I'd be looking for. Just my opinion of course, other people here have responded to it positively.