To rate, or not to rate?

Some of my fellow bloggers have decided not to give ratings on their reviews anymore, and so it is an issue I have been giving some thought to.
I really don't know which way to go.

I now have over 650 reviews on my blog and have been concerned for some time that my ratings generally range between 4 and 5.

For example so far this month I've read 10 books and the ratings look like this

• 4.5, THE OFFICE OF THE DEAD, Andrew Taylor
• 4.3, ANNA MARKLIN'S FAMILY CHRONICLES, Dorte Hummelshoj Jakobsen
• 4.6, INSPECTOR SINGH INVESTIGATES: A DEADLY CAMBODIAN CRIME SPREE, Shamini Flint
• 4.9, THE DARK WINTER, David Mark 
• 4.4, NO MERCY, Wendy Cartmell 
• 4.5, TUESDAY'S GONE, Nicci French
• 4.4, ANOTHER TIME, ANOTHER LIFE, Leif GW Persson
• 4.2, DESTINATION UNKNOWN, Agatha Christie
• 4.9, BLACKWATERCREEK, Geoffrey McGeachin
• 4.8, GONE GIRL, Gillian Flynn

With the ratings I can roughly rank the books, but I'd like you to tell me whether they actually mean anything to you.
I'm not at all sure there is very much difference between a 4.5 and 4.6 for example. It is still a subjective judgement affected by factors that I probably don't mention in the review (a bit like marking an essay - you'll know what I mean if you are a teacher)

In my own Guidelines I have said my rating are
5.0 Excellent
4.0 Very Good
3.0 Average
2.0 Poor
1.0 Did Not Like
0 Did Not Finish

Let me know what you think about what you would like to see by leaving a comment and participating in the poll in the right hand margin.

In my most recent review of COLD GRAVE by Australian author Kathryn Fox I have deliberately not given a rating. Read the review if you will, and let me know if you think it means less without the rating.