I'm still in the process of getting used to this keyboard, but have used the Microsoft Ergonomic 4000 in the past, and they are very closely related to one another. The keys on the new unit are much smaller and the feel is different. That 4000 has much more key travel, and the new Sculpt has a very short keystroke by comparison. Favorably impressed so far, but will continue to use it before making a final determination.UPDATE: After using the unit for a couple of weeks, I find it more comfortable and efficient than the 4000 that I was accustomed to previously. The layout of the keyboard is more compact, and as mentioned above, the keystroke travel is significantly less. Less strain to reach, less strain to press. While some of the reviews on this product have dissed the Function keys, those are not used by me all that much and the different feel/size is a non-issue. I know some of the other reviews have indicated dissatisfaction with the life expectancy of the unit. Mine is basically new, so can't comment on that area as yet.