Finally somebody in Microsoft got their head from the dark place and decided to do what had to be done. There is no more yearly subscription for developing Windows Store applications. All you need is a one-time fee of $20 (close to $25 Google charges) and you are set. All current developers are automatically freed from their yearly burden.
Microsoft wouldn't be Microsoft if they wouldn't release multiple editions. This time everything gets divided into Explorer, Expert and Master levels. Everybody, including those that already have published applications, start as Explorer. Quite a nice touch is that you immediately get Architecture and Design Guidance offers. I haven't tried it but it looks as if developer might get to discuss things with an actual human being. Sweet!
Going toward Expert level seems to depend onto you publishing your application and, I assume, well-being of that application. Master level is black magic and actual details are still somewhat fuzzy.
It is really hard to tell whether this will improve Windows Store or not. My bet is that it won't change much immediately because Microsoft was giving registration benefits for free even before. Every single developer I know that had Windows Store application published, got to do that at no cost. Rumors are that some were even payed to do it.
Official removal of subscription does lower the bar a bit for hobby developers who, seeing the $100+ cost per year, just gave up and dealt with Android instead. If Microsoft gets those guys interested in platform again, I can see many new applications coming in. Yes, most of them will be bad (as they are in Android store) but with time store will get bigger and there will be more enthusiasm. And that will bring better quality.