Wow. I downloaded it to try out for fun. It's TONS better than I remember it being on the Nexus 4.
Google's really going crazy with their minor but frequent upgrades to their apps. I'm loving these upgrades.
Swiping is so much better now on the stock keyboard. I'm very impressed. As is the ability to slide to get to the symbols. The little line that follows you when you slide to the symbols is great. Auto prediction and correction seem better, too.
Might give this a go. Doubt it'll dethrone Swiftkey, though, but will try it for a few days.
PS. If Apple doesn't announce any sort of upgrade or revamp of the iOS keyboard on Monday, I will laugh, and then shake my head in sad disappointment. Wouldn't mind seeing some sort of swipe-like functionality, too. They're so behind in this department, it's absurd.