It's hit or miss in my experience. I've had a couple of campaigns that have killed it on Gemini, but most end up being trash. Try to use words in your headlines that are similar to things that are going to be prevalent in the news - I had "Obamacare" in one headline and it got a ton of traffic, I think they decide to give you impression based on the perceived relevance of your to the page where it will appear. This was when Gemini was brand new though, I know targeting has changed and maybe so has the way they determine where you get impressions.