Pretty cool demo, what I wonder about is how the quality is and how long they can keep updating their tiles. My experience last time I did something similar was

Pretty cool demo, what I wonder about is how the quality is and how long they can keep updating their tiles. My experience last time I did something similar was that the OSM data grows fast, the import and rendering takes longer and longer, and something tends to break in the process or create rendering problems in some random countries if you don't spend time checking. A more obvious quality issue for example: on their demo, Arabic text renders wrong (left to right instead of right to left, it'd be like printing kroY weN instead of New York)