Really? I don't think so. I get a 0.9 on Google Chrome, and a 0.7 on Firefox. I heavily use Chrome and I have not used Firefox apart from maybe testing some local websites. Despite this I still got 0.7 on there. I expected lower since I don't use the browser.
I was being sarcastic - high score on captcha probably means G knows too much about you. That said, I don't think the scores are reliable. It is possible (probable even) that G is still running experiments.
This is essentially going to let Google gatekeep the web if you aren't using their services.