Mine is glitchy... Typos and text prediction not working properly
Always used Samsung keyboard on my note 5
Now had to switch to SwiftKey on my note 7
And I have to say
It's one amazing keyboard
Very comfortable feedback is amazing and text prediction is great too
I use the default Samsung keyboard on my Note 4 for all the typing work I need to do. It works extremely well in all of the apps. The swipe feature works flawlessly. I would suggest you to dig in the keyboard settings a bit more & to fix issues, please Clear Data & Clear Cache of the 'Samsung Keyboard' app via Application Manager.
If still it does not work as it should, perform a 'Wipe Cache Partition' from phone's Recovery Menu.