Percentage aside, I think it is perfectly reasonable that Google reserves a lot of space for ads. What pays for the search results after all? I am surprised that people expect to get great service for free. It's just not sustainable.
What is not reasonable is how deceptively similar the ad looks to an actual search result. If Google is confident about an Ad being information then why not let people click it for its relevance? Why make the background just barely different from the search result so that its almost impossible to visually separate ads from results? Let people clearly know that its an ad and let them decide whether they want to click on it or not.
Bing is as deceptive as Google here so not singling you guys out but please don't portray a reasonable effort to make money as a something larger than that.