There are very few good provider libraries out there, making it harder to stick to standards. People who want to provide an API shouldn't have to re-invent the wheel every time.
I started writing opro before DK was out in the wild. There were some things I had in opro that weren't in DK so I decided to keep developing it.
Last time I checked here are some differences:
- Deals with CSRF protected resources automatically
- Works with your login system (like devise), not around it. No special casing or configuration is needed
- Comes with built in docs.
- Comes with built in test controller
You can play around with it here: http://opro-demo.herokuapp.com/.
P.S. - it also took like six hours of banging my head against a wall for unrelated oauth-related problems, but not DK's fault.
Enjoy.
I agree with the main thrust of the argument though. OAuth providers do not make it as easy as they should. The point about the buttons is spot on. I've had some good success with the buttons provided here:
http://nicolasgallagher.com/lab/css3-social-signin-buttons/