Yahoo should be ashamed of itself, and as far as i'm concerned, subject to a hefty fine. I am NOT swayed by the argument that yahoo mail is a 'free service' and so we're only entitled to shitty service. In fact, it is not a free service, because Yahoo is making millions of dollars by mining all of our personal data. We deserve effective service for allowing this corporation to make money off of us.
Furthermore, if Yahoo knew that it was going to be putting email accounts out of commission for a substantial length of time, it had the responsibility to announce this to its customers. Many people rely on their email account for important communications involving their work, paying their bills, etc. Putting email accounts out of service for hours at a time without warning isn't just an inconvenience-- for many it's resulting in lost wages and productivity, and potential problems with bill collectors and service providers.
I have used yahoo for over a decade, but am strongly considering changing to a different provider. I'm looking for a company with a little respect for its customers and basic efficiency in its services. I'm not certain that such a company exists, but Yahoo is proving that it certainly doesn't care about its customers.