Wii U players are outraged that the first Virtual Console title, Balloon Fight, runs at 50Hz frequency despite the existence of 60Hz versions.
Before the transition to digital TV, PAL was the standard used for analog TV broadcast in Europe and Japan while NTSC was used in North America. One of the main differences between the two standards is that PAL operates at 50Hz while NTSC operates at 60Hz. This difference in frame rates makes PAL games run 17% slower than NTSC when played on modern digital TVs.
Currently, Balloon Fight Miiverse is filled with angry messages criticizing Nintendo for porting the European PAL version of the game instead of the North American version which runs at 60Hz. Fans have already started a petition asking Nintendo to make sure all future Virtual Console titles are ported from 60Hz versions.