I read the first of his trades, "Scab" the other day. I was surprised at how good it was. It's not Delano/Ennis/Campbell/Jenkins/Ellis/Azarello/Carey/Diggle standard in my book, but at least it's not as bad as the scottish woman's stuff (which, to be fair, wasn't completely dreadful - just not that great, which was a surprise as Constantine's only ever had a few bad writers - and most of them didn't do much).
As you say, Trout, Constantine works best in a run of issues. Which is the reason I usually wait for the trades.