I think the rating system on Goodreads is reflective more of the readers’ experience of the book rather than their opinion on the book’s quality. I admit I rate the books I read based on how I felt while reading the book and after. So it won’t really say much about whether I find the book well-written, well-paced, etc.

On the other hand, some reviews are very helpful and I would use them to determine if I will check a book out.