I do like GBoard quite a bit. I love the quick google search that you can access right from the keyboard. That's slick! It also runs very smoothly, more so than SwiftKey, which can be a little wonky at times. I'm not sure I can make a full migration from SwiftKey to GBoard though. There is one thing that has been driving me crazy about GBoard. You can double tap the spacebar to get a period, just like you can on Swiftkey and that's great. After the period is inserted, it leaves you with a space so you can go on typing the next sentence. However, when you use any other punctuation (comma, exclamation point, question mark) it does not leave a space. I'm so used to Swiftkey doing this for me that it really drives me nuts that GBoard doesn't do this and there is no option that I've seen to make it do so. Why would I ever not want a space after a comma, exclamation point or question mark? I know it sounds like a small gripe but I've been typing with SwiftKey for years and can type fast without looking. This just screws me all up. If they could at least make an option to insert space after punctuation, I'd probably seriously consider switching.
With that said, it is an awesome keyboard and if that doesn't bother you, I do feel that Gboard runs more smoothly than SwiftKey. SwiftKey is virtually glitch free now but every once in a while I get a small bit of lag/wonky behavior.