I wonder how frequently this will be updated. I notice several skyscrapers built over the past few months that aren't displayed yet (they only show the construction huts). So it's at least several months out of date.
This clearly has the most detail for zooming and browsing that I've seen, but for my day-to-day use I'll still be using map.sogou.com, which already has pretty good building and landmark decomposition, but has the best path-finder / location search of everyone in the market by far. I just made several queries on bj.o.cn that fell flat. For really hard-to-find places, I suspect I'll do my searching on sogou first, then pull up the closest landmark on o.cn and scroll over to where I want to be for a good visual description of where I'm going.