Got the new Bona Whirl about a week ago.  Just used it over the weekend.  It is definitely much easier to refill/attach the bottle.  The single release button is also very helpful.  The microfiber cloth is larger than our old Bona.  At first my wife thought it was harder to push, but after temporarily attaching an old cloth I attributed this to the fact that it was new and had higher friction.  Another thing I liked was the retractable hook at the top of the handle.  We always hang our mops from the wire shelving in the laundry room.  One improvement I would like to see is enclosure of a pamphlet in the package which contains the same information that is printed on the box for better retention.  Other than that, I thought it was a great product!