I installed "download chrome extension" it allows you to add chrome extensions to opera 21. I then installed "RSS Feed Reader" from the chrome app store. Its working great for me so far. I also installed adblock, passlink, and privacy badger (privacy badger is from the chrome store) without any issues. I'm still trying to figure out how to skin this browser without any luck at this point. I hope they allow skins soon.
I hope that helps!