SPDY was great for Google and allowed them to change and take hold of HTTP/2.
It saved them lots of money I am sure in improved speed but at the trade-off of complexity and minimal adoption of the standard because it wasn't beneficial to everyone. HTTP/2 is a continuation of that effort by Google which I would do if I were them as well probably. But in the end both are not that big of improvements for what they take away.
Of course I use both but I don't think they will last very long until the next, it was too fast and there are large swaths of engineers that do not like being forced into something that has minimal benefits when it could have been a truly nice iteration.
HTTP/2 is really closer to SPDY and I wish they would have just kept it as SPDY for now. Let a little more time go by to see if that is truly useful enough to merge into HTTP/2. HTTP/2 is essentially SPDY from Google tweaked and injected into HTTP/2 which has huge benefits for Google, so I understand where the momentum is coming from.
Google also controls the browser so it is much easier for them to be the lead now on web standards changes. We will have to use it if we like it or not. I don't like the heavy hand that they are using with their browser share, just like Microsoft of older days (i.e plugins killed off, SPDY, HTTP/2, PPAPI, NaCL etc)
SPDY is a great prototype that exemplifies why you should write a prototype: to show the problems with your design. It's unfortunate that the HTTP/2.0 committee decided to ignore the flaws and go with the prototype design.
