We have an integrated picture upload mechanism from postimage.org here at SAS, so for uploading an image every other day there's basically no need to use anything else.
If you're frequently using images for specific projects or want to categorize your images or even are some kind of artist, other services are useful of course.
I'm using flickr for quite some time now and never encountered any issues with their free service.
Neither did any image suddenly disappear, nor have there been any restricitions on image hotlinking.
Best regards - Mike