So I've been on Flickr for a while, but I hear all the cool kids are hanging out here on 500px as well. So far, I like what I see.
I like the notion if creating a personal portfolio webpage that looks good
Interesting notion of grouping by tags
No Lightroom plugin for uploading
No concept of groups or communities
Voting is anonymous (or am I missing something...?)
All in all, I think I'll stick around. I'm excited and think this will be a rewarding place to show my photos.