Next time that an adwords advertiser says that the adsense program does not convert and that it doesn't work for anyone. Point them to the following thread, where so far two advertisers have shared that they are happy with the conversion rates from content ads.
Just as with publishers, AdSense will work very well for some advertisers, very poorly for others, and will fall somewhere in between for everybody else. Ultimately, advertisers will opt in or out of the program depending upon how it works for them. We are far more likely to hear from those who find AdSense or AdWords to be problematic, than from those who find it to be adequate or good.
Every time Google changes its policies or algorithms, some people will find those changes to be positive and others will complain that they are negative. There will often be truth to both sides. A change which increases the relevance or profitability for one publisher may have the opposite effect, or result in vastly increased PSA's, for another. A change, such as broad matching, which may significantly reduce the average cost per click for one advertiser may significantly increase the cost per click of another.
Ultimately, given the relative ease by which people can track the performance of AdSense and AdWords, the market will dictate the success of those programs, and additional changes will occur as Google attempts to improve the programs to maximize profitability and relevance. (And with every change, no matter how minor, we are likely to hear complaints.)