Quote from enemi
Hello, I'm playing on the US servers from SEA and I have 400+ ms.
Don't worry, it's still playable.
Just a little annoying with the delay in attack and movement times, most specifically the item pick up.
It really is very playable compared to what you would expect with most games. I usually have around 99-230~ ms throughout the day on Diablo III (averaged from stable times today and beta experience), but for the past several hours I've had anywhere from 250-360ms. It will go down, but you really barely notice it.