I do consulting work and am regularly given an account on the company's email system. More recently they're using GMail underneath, so now I've apparently got a dozen accounts on GMail.
And GMail, bless it, when I login through the company's system clocks me through to a "Choose which account" system. My reaction is to open a new tab and login again, and it usually takes me straight through to the actual email without repeating the request for credentials.
The whole thing feels clunky, slow, and confused underneath. I don't much care about the look, that comes and goes, fashions change, but the experience as a whole has become painful.