I use Flickr because of the ease to upload photos to the site. I can upload form my computer and iPhone. I also like it's capability to place photos in multiple sets, and sets in multiple collections. For example, hiking photos can be in a Whitney set *and* a Family Vacation set if I wanted.
The free version of Flickr is kind of a brain dead version - limited photo storage and limited upload bandwidth/capacity. If you take a lot of photos, then it's worth paying the $40 a year for the full version.
http://www.flickr.com/photos/glennsphotos2007
