They capture my keyboard after I search from the menu bar of Chrome, so I can't hit backspace to return to the previous page. Even if I click outside of the box, any Google search page redirects my backspace into the search box, which also changes the results.
My issue is I almost always search from the address bar of chrome, or the search box of any other browser, so I never see the "instant" effect. I can't remember the last time I actually went to google.com except when linked to see a cool logo design.
Yeah, they broke one of my search patterns: search for something, read the answer from the results. I do this almost as much as following any of the results, because for a quick answer to a question the answer is usually in the summary of the link. Now, however, I open a new tab, google loads, I type the question and hit Enter, and when I CMD-W to close the tab, Safari stops me to ask if I'm really sure I want to do this.
This seems like such a tiny thing while I'm writing it down, now, but it's frustrated me steadily today; I've context-switched out of whatever I was thinking about more than a dozen times to figure out why I was getting a popup warning. Finally I just turned it off in search settings. The barely-noticeable increase in speed just isn't worth it.
It's rather quite annoying.