I use a 5-pt scale, with .5′s. The minimum a book can get is a 1 and the max is a 5. All the books on my Favorites page are 5′s.
1 — Terrible. Or just not the book for me. I’m thinking “well, this is annoying” the whole time I’m reading it
1.5 — I obviously did not like it.
2 — It might have had a couple of redeeming features.
2.5 — It had potential, but just did not meet expectations.
3 — All right, but I won’t read it again.
3.5 — Some parts may have been good, but it wasn’t as good as it could have been.
4 — Pretty good.
4.5 — Almost perfect.
5 — This is a book that absolutely became a part of my soul and I will add it to my favorite’s shelf