What counts as a review on goodreads is not always the same. On the book page and on the profile page, the number of reviews counts any text in the review field. The first reads program expects a review of at least 50 characters, if you win a book.
Often it is more of an opinion of the book rather than a critical evaluation and sometimes it is just information about the book (often written before the release date), or it could be a personal note, such as who recommended it or where they heard about it, or even that they can’t wait for it to be released.
If you connect your facebook and/or twitter accounts and let it post reviews automatically, it does post reviews and ratings, but it also posts every time you add a book to your bookshelves. Your friends and followers might prefer that you uncheck reviews on the account apps page and just check the facebook or twitter box on each review you write.
Clicking on edit review, gives you access to more than just the review fields. The private notes field and a field for who recommended it is there. If you check I own a copy at the bottom of the review page, another set of fields (bookswap, condition, purchase location, purchase date, and bookcrossing id) appears.
Many people rate books without writing reviews and some people write reviews without rating the books. Some people even mark books as being read (often books they read long ago) without rating or reviewing them. You can do whatever works best for you.