Frustrating, sure. Something to be "angry" about? No.

Its a free service. With no advertising. When you use Tumblr you are consuming their resources which they are giving to you free of charge. Its not like they deliberately pulled the plug either. They can deal with the problem in their own way.

Honestly people need to get over this sense of entitlement to online services. We should feel blessed that Tumblr or Twitter or Facebook or HN exist, for free, in the first place.