I love my knook! I'm finally able to do all those charity knit patterns I've had my eye on for ages. I love crocheting but could never make the jump to two sticks (the 'proper' way) so assumed knitting was for others and never for me.
The knook changed all of that! With the same movements as crochet I can now make knitted fabric AND it's faster than knitting ever was for me. I don't have to worry if I have to get up and leave my work- or even roll it up and put it in my Yarn Drum to head out to a friend's house- I don't drop stitches at all.
One thing I would change would be to offer options on hook design. I have been crocheting long enough to have a preference in hook styles and it would be lovely to have that option with the knook too. Perhaps a 'slim line' hook design and also a 'straight line' hook design option?
I'd also love to see an aluminum option as bamboo isn't perfect for all yarn fiber types.