p.s. I do use HTTP/2 and install it for my clients. One might face minor issues with HTTP/2 on a number of browsers and mobile devises in certain cases. And still HTTP/2 is good.
p.p.s It's not a magic and won't increase speed of PHP+MySQL as one might think.
HTTP/2 supports queries multiplexing, headers compression, priority and more intelligent packet streaming management. This results in reduced latency and accelerates content download on modern web pages.