On my iPhone 5, typing using the slide gestures took way more effort and thinking than simply typing normally. I tried it for about a week and didnt see much improvement.
The autocomplete is very poor compared to the one on the regular keyboard, which is especially needed if you want to be sliding around the keyboard. Also, the emoji conversion needs more words for it to be practical (eg the poo emoji doesnt come up with the word poop)
There are some nice features, but overall its quite cluttered and the learning curve is just too steep. There are many features that all collide with each other, making for a very confusing and frustrating experience.
I realize that there was a lot of work put into this keyboard, but it seems too expensive for a product that is so difficult to use.
Lorenzo45 about Nintype, v1.3