for all that WordPress is almost the single most successful project the internet has ever seen, Automattic has never done hosting sites (not services) themselves very well. i cannot remember the last time i have seen a single person use or care about WordPress-dot-com.
i am not very enthusiastic about their ability to understand the things that made Tumblr good and reinforce them after years of atrophy, but nor am i very apprehensive about it. it’s a solid We’ll See.