This is my keyboard. It's just a few months shy of 22 years old, and I use it every day.
The first thing that may strike you about the Model M is the layout: It's so normal. There's no pesky "Windows" key here; nor are there buttons to turn your computer off, play a CD, or start your car. Just the basics, as IBM defined them 24 years ago. Some would say its only flaw is the prominent placement of the Caps Lock key (in lieu of "control" on earlier keyboards). But it's a minor error compared with the modern keyboard's multitude of sins.