The new version of the Flickr app is pure awesome, though. Even the login screen is beautiful.
Once you login, you're presented with a page of photos from your contacts. Scroll sideways to see more photos from each contact, or change the layout for a justified view of photos from all your contacts. You can also browse groups you're involved in from this screen.
Explore interesting or nearby photos, view your own photo stream and activity, and find friends from your address book, Facebook, or Twitter. If you're all out of friends, Flickr will suggest some people to follow--just select 6 photos you like from a list.
Uploading photos now includes the ability to edit with Aviary, or add Instagram-like filters before uploading.
It's a huge update, and definitely worth checking out. Especially if you abandoned the app in the past.