I have one for work and absolutely hate it. No tactile feedback at all, so it's easy to mis-hit a key. I also echo the guy who said he accidentally hits Siri now because of it. It happened to me A LOT until I realized you can change what shows on it by default. Now I keep mine with expanded controls at all time. It's still annoying because I have to look down to be able to press the right key. I prefer having physical buttons.
EDIT: ALSO the keyboard itself is AWFUL. The absolute WORST keyboard I've ever used. It's terrible to get stuck typing on.
"stuck" -> The tiniest bits of dust or crumbs makes keys still and not work. It's super annoying to blow on the keyboard to try to get a key to start working again.
According the ATP.fm the only safe way to clean the dust out of it is to take it to an Apple store. You can easily destroy the mechanism if you manage to pry the keys off.
I imagine this will be fixed in the next iteration though.
I felt the same way about the new butterfly keys for the first 15 minutes or so, but very quickly got a feel for them and now I prefer them to the keys on my mid-2012 MBP.
I quite like the click sound they make too, it's mechanical and satisfying, although it's a little loud for quiet situations like libraries etc.
EDIT: ALSO the keyboard itself is AWFUL. The absolute WORST keyboard I've ever used. It's terrible to get stuck typing on.