I think with a few minor enhancements this tool could be even greater, but, as said, it's quite perfect already! Thanks guys for sharing this!
One of the things I don't like, is that any time you make a minor change to an article, all the likes and shares disappear. I suppose the same happens to comments, although I haven't tested that because I don't want comments on my site. I tend to change articles for a while after I've published them. That means that every time I change even just metadata, I loose all the cool thumbs ups! I understand this from a business logic perspective: It isn't the exact same article people voted for anymore, but I'd certainly like it to be different!
A minor problem I've encountered is that sometimes the article picture isn't picked up, and sometimes the article meta description isn't picked up when sharing. Cancelling the share and retrying a few times seems to do the trick however.
Over all, a good extension!