I enjoyed 'Quite Ugly One Morning', I thought it was very funny and worth at least 4/5 from me.
There's an extract on Brookmyre's site, though you may want to reformat it (
contains rude language 
):
http://www.brookmyre.co.uk/book1.htm
together with some sample of reviews. I chuckled over:
"Huffiest comment: "Deeply unpleasant and thoroughly nasty... the novel makes for somewhat tedious and disappointing reading." Allan Laing, The Herald"
Well done Brookmyre for including the less than sparkling critiques.