MY PERSONAL RATING SYSTEM
Here at A Little Reading, I don't rate every book I read. But when I do rate a book, I use the following point (or stars)/grading system:
✭✭✭✭✭ (5 stars / A+) = Loved it. My "desert island" category - all-time favorites that I wouldn't want to be without; not many get this rating.
✭✭✭✭ (4 stars / A) = Really liked it, would recommend it; would read this author again.
✭✭✭ (3 stars / B) = An enjoyable read, but nothing extraordinary; most books will fall into this category.
✭✭ (2 stars / C) = It was OK, I might or might not recommend it to others.
✭ (1 star / D) = Mediocre; disappointing; had trouble finishing.
(I don't have an "F" category. Most of those books would fall into the DNF category, since I almost never try to struggle through books that would rate an F.)
DNF (Did Not Finish) = Books I started reading and then abandoned or put aside. This doesn't always mean I didn't like the book, just that I wasn't able to finish it or didn't feel like continuing with it. Might or might not finish it later.
If you read my reviews, you'll notice I sometimes show the rating as stars, sometimes list the rating as points, sometimes as a grade. I'm making an effort to be more consistent with this, but tend to backslide. Also, I haven't always used a rating system with my reviews -- again, I'm trying to be more consistent now. But it's a struggle.