I've made it possible to import all your shared or starred articles from Google Reader into Pinboard. You can find step-by-step instructions for this on the import page

The shareable social object of subscribe-able items makes Reader’s network unique and the answer to why change is painful for many of its users is because no obvious alternative network exists with exactly that object. The social object of Google+ is…nearly anything and its diffuse model is harder to evaluate or appreciate. The value of a social network seems to map proportionally to the perceived value of its main object. (Examples: sharing best-of-web links on Metafilter or sharing hi-res photos on Flickr or sharing video art on Vimeo or sharing statuses on Twitter/Facebook or sharing questions on Quora.) If you want a community with stronger ties, provide more definition to your social object.