When the cover does its job

I picked up John Burdett's 'Bangkok Tattoo' simply because of its cover - a simple three colour, but striking art work (that wraps round the book).  The back cover blurb then did its job.  I'm about halfway through and so far it's living up to expectations and I'm thoroughly enjoying.  The cover art certainly did its job (and it does have a job to do, though you wouldn't think it given the generic, non-statements of many books).