Usually when I hear this opinion of AdWords, the root cause is due to either running campaigns in house without the appropriate knowledge, or having a bad experience with a “pile ’em high, sell them cheap with hard sales call tactics” type agency. Running an AdWords campaign without knowing how to use the platform can be a recipe for burning money fast. With the first campaign I ran for a client, I saved almost 50% of their ad spend within minutes as they were serving ads for completely inappropriate search terms.
For another client who was running their campaigns using a generic Google helpline, I halved their cost per click from $2 to $1 meaning they were previously spending twice as much money as they had to. It is also not uncommon for me to take an internally managed AdWords account and change the average clickthrough rate from 1-2% to over 10% (and sometimes higher), and get results that return many multiples of ad spend. All of those are good metrics but I’ll also sort out your conversion tracking so you can track monetary values, which is the ultimate metric to measure.