Anyone who thinks Yahoo buying out Tumblr is a good idea needs to look back on when Google bought out Youtube. The format changed and Youtube (GOOGLE) began taking content down as it saw fit. This is how monopolies are formed.
Edit: Yahoo plans on having ads run on Tumblr. Isn’t part of the gloriousness of Tumblr that it’s ad-free?
Do some research and don’t take things for face value.