It's not a bad read. It certainly rattles along at a fair old lick. My one criticism would be that it's impossible for the reader to guess that there'd be a plot twist at the end. Most authors give away a few clues as to the why of a crime in their books, but that doe4sn't happen here till it's all gettin wrapped up.
Incidentally, I wouldn't start the series with this book. Not because it's bad, but because it gives away plot elements that occur in books that appear earlier in the series.