I use Flickr to dump all my photos on to then use 500px to share the photos I like the most, the dislike function is a bit of a pain when you get to no1 page in popular then 10 mins later you can be on p3 because the dislike is kind of used as a 'get out of my way button' more than a bit of critique on a photo that needs it, ive seen some exceptional work on there hanging around the lower ends because as it was rising some troll decided to dislike it out of spite and down it goes into the pages that nobody really sees which is a shame as it then wont get the views it deserves.
Saying that I still think the best place to showcase your best work to the world and is worth the money for the account.
http://500px.com/bridgephotography