The ultimate social tool is talking about a book (or any other kind of resource, including journal articles), whether by leaving a review on a library catalog, a blog, Twitter, a bookselling site, or discussing it over the dinner table.
Search It/Primo Users:
There is no ability to add or view reviews in Search It (Primo) but if you click on the Details tab for a book or movie, you will see links to WorldCat (Open WorldCat) and Amazon on the left side of the record.
Books may already have Editorial Reviews (i.e. from Publisher's Weekly) but any type of publication can have User-Contributed Reviews (although if the item is a book it will also pull in reviews from online social bookshelf websites WeRead and GoodReads, as well as online bookseller Amazon - see this incredibly academic example). You will need a WorldCat account to contribute a WorldCat User review - this can be either an account created in WorldCat.org (Open WorldCat), or in a WorldCat Local library catalog (see the WorldCat Social library guide for more information about WorldCat accounts)..
You can also tag a book or other item, and see all the other resources that have been tagged with the same term (at this time tags are not included in the WorldCat search algorithm).You will not see who assigned a tag to a particular item when you are looking at the item; however if you are looking at a WorldCat profile you can see what tags the user has created, and the items they have tagged with each index term.