It looks like you're new here. If you want to get involved, click one of these buttons!
Apparently the Korean players have severe log in issues because the Chinese players play on their servers too and Blizzard never placed servers in China. With as result that the Korean servers are severly crowded. The Korean players that demanded a refund because of this were refused. So now their country's FTC is looking into this lol.
"While Diablo III might be a big hit in South Korea, the country's Fair Trade Commission is looking into allegations that Blizzard refused to refund Koreans who purchased the game and were frustrated with overloaded game servers. "
Might want to check the related topics there too.
I really hope that those server issues will be resolved soon for the players. But even more I hope that Blizzard will release an offline mode for single player and that upcoming games don't pull this online only crap for single player experiences.