I'm an independent software vender (develop and sell my own commercial software) and I've never had any success using AdWords.  I had one highly successful product which I could never do better than break even when promoting with AdWords.  I even hired a highly respected AdWords expert to manage my AdWords campaigns and again I only broke even (and that was BEFORE paying the expert so it was actually quite a loss).  More recently (in the past year) I gave it another try with another software product and again had no success (both with my running the campaigns and with another person I know running them for me (a friend who swore by AdWords).

I'm wondering how many people are successful using AdWords vs. how many are unsuccessful.  I've hear many people say it's indespensible for their business but suspect that there are many more who lost money with it and quietly gave up...