It is really similar, and even lets you import your shelves and reviews from Goodreads so you aren't starting from scratch on your to-read shelf or recommendations. The main downside is that it is new and not many people have migrated over, so it is harder to connect with other readers. But the core features - book pages, reviews, recommendations, "buy" links - are the same, except for the fact that when you buy through a StoryGraph book page you're directed to Bookshop.org, which supports indie bookstores, instead of to
Amazon.