I like them all I'm a big Tony Hill fan. This was a sequel of sorts as its Karen Pirie again but it didnt feel like it was suddenly going to be ongoing! Maybe another 6 years before another one.
Sorry. (Not sorry really) If you've missed many, on the Tony Hill side of things it won't matter that much except you need to read "The Retribution" followed by "Cross and Burn" as the two are linked quite closely in the ongoing storyline for Tony and Carol. Apart from that little tip go for it! I don't think you'll be disappointed :)