I have been somewhat unhappy with my old Logitech keyboard for a while now. The actual act of typing on it never felt good, it had some neat multimedia features on it but it never excelled at being a keyboard though. The new aluminum keyboard from apple is a pleasure to type on and still can do most of what my old keyboard did too.
One thing I have always liked about laptops was the short key travel that they had, I could always type much faster on them than standard keyboards. All the other external keyboards that I have seen that mimicked the laptop style were just straight copies of the layout though. They usually lacked such things as a number pad or were so cramped that typing was difficult. While this new keyboard is also tiny compared to my old one it fits all the keys needed with enough room to not feel like they were trying to shove everything in.
Even though it is an apple keyboard it works fine under windows too. There is an application called SharpKeys that allows you to remap the scan code from any key to that of another. I used this to make use of most of the media/function keys to control winamp since I never use F7 and above. Since it also goes up to F19 the extra keys were mapped to other useful functions too.
My only complaint is the box that apple shipped it to me in. Had the box been an inch or two wider I think they could have fit about 30-40 of the smaller cardboard boxes that held the even smalled box that the keyboard was actually in.