Rating System?

The idea of a personal rating system for books appeals to me.

However, my rating may be completely different than yours.  Even with such helpful questions as:

§ Was the author able to impart the story in such a way that the reader is not distracted by the words themselves?

§ Does the book contain wonderful descriptions that carry the reader away from reality to another world?

§ Did the author’s presentation of the book’s content have an undertone of meaning, such that the reader is left feeling that they have learned something important by reading the book?
(from Inkweaver Review)

My ratings (and thus reviews) tend towards more subjective rather than stylistic and plot issues.  If I would read a book again, for example, then to me it's an excellent book.  Something about the book has caught me.  But someone looking at the plot and the characters might find them cliche and cardboard-y, thus giving a completely different (and probably poor) rating... 
 
On the other hand, I also read a lot of non-fiction.  Non-fiction (for some reason) I am able to look at more objectively and say yes, that was terrible research, hard for a layman to understand, excellent narrative, etc.  (Then why is that so hard for me to do with fiction books?!)
 
That being said (after looking through good ol'Google's results), I think I've decided on the following for a general rating system:
 
1 star (*) Terrible/DNF - speaks for itself!
2 stars (**) Disappointing - I finished the book, but it was a long time in coming...
3 stars (***) Average - Interesting, but I've read better.  If you want to read it, get it from the library!
4 stars (****) Good - Better than average, but not quite excellent.  Buy it only if it's on sale or at a secondhand shop.
5 stars (*****) Excellent - a definite purchase/re-read...this is the kind of book you can't stop thinking about!
 
(Oh so unique, isn't it? ;-)  Does that make sense?  How does everyone else rate their books? 
 
I know the 3 and 4 star ratings are going to give me trouble (i.e. "is it a 3 or 4?"; "this was good, but this wasn't"; etc.), and the 1 star will be rare (mainly because I'm picky!).  I'll give it a test drive and see how it works out...
 
Jenn ;-)