Lol did you install a 3rd party keyboard or something?
They're not ready.
My keyboard works perfect but its the stock keyboard. No input lag, if thats what you mean by input lag.
Keep in mind I'm talking about an initial delay. It works great most of the time once it starts responding.
When the keyboard pops up, there's a good delay before it allows you to start typing. This is the part that I really dislike.
It isn't just the keyboard either. Every OS animation causes the input to be ignored. It was really bad on 7.0, but it's still there. It limits how quickly you can use the device.
If you don't ever notice it, that's great. But it's there, and anyone who uses their device quickly is sure to notice it. I often forget how much worse it is than an iPhone 5 on iOS 6... That thing is blazing fast compared with my 6.