Funny, I work 9-5 and haven't had a problem logging in after work short of when it was released an am currently level 58... Haven't had a problem this weekend either. Latency is fine for having to connect to an American server. Also to be fair as long as you have friends you don't even play this game by yourself. Pretty much exactly the same as D2.
Maybe people should read the notice on their login screen so they aren't trying to login during scheduled maintinance. Considering this app is just parsing what is already available on the Blizzard website it's not like it's anything out of the ordinary.
Haters gonna hate.