Well my understanding is that it is the Holy Grail of modding when it comes to the ability to create all sorts of different types of games that have nothing to do with the original...
Not really. The maps are limited to 20mb each, removing the modders' ability to go crazy. While you can craft some interesting maps, they are one-shot deals - the FF Battle Mod, for example, isn't an JRPG mod, it's merely a battle mod. As each user is limited to a mere 5 maps - all of which must not take up more than 20mb - and that all maps must be stored on Battle.net, any hope for the custom content scene died before the Beta was finished.
When Blizzard finally annouce the subscription-based Premium
Battle.net accounts, which include larger map sizes, then you'll see the addition of the Map Store. Anything that could be worth playing will cost you, and all access will be remove if you don't continue to subscribe due to the maps being stored on Blizzard's servers.
The editor was a nice idea, destroyed by complete incompotence.