|Actually "Y U NO READ?" might be a better question, but anyways...|
Intensity - I should be completely emotionally engaged, be high on adrenalin throughout the book (especially during the climax) and "book hungover" when I finish.
Pacing - It should be very fast paced - slow thrillers either bore me or drive me nuts
Originality - It should be more than your standard serial killer fare. It should have a unique and creative premise that works well in practice as well as in concept
The Basics (characters, plot) - the characters should be well and properly developed, the plot should without holes or logic errors, stuff like that
Sex - as Clive Cussler once said "sex kills suspense". Nuff said
Language - a good thriller shouldn't need to use foul language to be "realistic".
And now for my top five thriller authors
1. TIE between Steven James and Robert Liparulo
3. Robin Parrish
4. Michael Crichton
5. Alex Scarrow