It looks absolutely terrible and is laggy and annoying, but that seems to be the current "professional" bandwagon. It's trendy, and that's all that matters. I just wish they'd quit screwing with Classic Yahoo! Mail. They keep throwing in useless Ajax everywhere, which means 90% of the links now can't be opened in a new tab, so I have to open a new tab, go to Yahoo! Mail, then click the link I want to go to.
Also, that damn exclamation mark in "Yahoo!" is annoying as hell. Does anybody else hate random useless punctuation in company/product names? There's a restaurant called "Souper! Salad!" here. When I read that, I read it as two separate sentences, and it sounds painfully retarded. Same with "Godspeed You! Black Emperor," whose name I only know because I read it one time and thought, "that sounds stupid as hell and makes no sense." And then Yahoo! goes and makes me end my sentences before they're supposed to end 😡