Personally, I like it.
I occasionally write short reviews (good pracitce for Japanese)
More often I just leave a star rating (while not implemented on the side, you can always just put the symbols as a review)
I also enjoy reading some of the reviews left by others which also helps me learn how to talk/write about books.
If you have lots of physical books, they have an app where you just have to scan the barcode to add it - very nice.
However, if you haven’t started bookmeter yet, https://booklog.jp/ is also an option, which has the added benefit of import/export functionality, if this is something you might want. (Bookmeter doesn’t offer this.)
