I used to like Yahoo's mail service, but they made a lot of changes last fall that made it worse, so I, too am phasing out of Yahoo. I wish they had heeded the old saying that if it ain't broke, don't fix it.
The huge changes to the Yahoo mail service were put in place by their new CEO, who, like all new brooms, just has to sweep everything clean.
The Yahoo using public HATES the new changes. Find any discussion thread about it, and you'll have a hard time finding a single complimentary comment. The public has been screaming at the top of their lungs about it for months now, and Yahoo hasn't done a thing to abide by their customers' wishes.