I like that it has been easy to integrate with our product, which helps keep us ahead of competitors in this space! Their support team was quick at responding and always willing to help out or give advice where needed.
We haven't found any downsides yet either. Overall we are happy so far - would recommend them if you're looking for an autocomplete solution! They have made integrating their service very simple by providing API keys straight away. It's also helped greatly with SEO since Google now shows results quicker than before thanks to having more relevant content showing up first.