I always hear people around commenting Lenovo ThinkPad (formerly IBM ThinkPad) series is great, but they are rarely buying one just because of "the red stick" in the middle of one of the best keyboard ever. I were among that group of people as well; however, time changes; people also change too. Ever since I got my X61T, I had been forced to live with the only choice of mouse called "TrackPoint". I have started changing my mind then.
Everybody around me knows that I naturally hate using touchpad. You will hardly find me using touchpad. Thus, I'm always carry a little USB mouse with me since I have a laptop although that loads me a bit more. However, it doesn't mean I use touchpad as slow as one who haven't ever touched a computer. The thing has been changed since I got ThinkPad X61. From the very first feeling of using TrackPoint, I did feel somewhat awkward and found it not as fast as my weak touchpad skill. But it was just a time when I was a stranger to TrackPoint. For the time being, TrackPoint is a breeze comparing to touchpad and unfortunately better than a mouse in some ways.
To get into why it's so good, you may have to know a bit of how it works out. In order to move a cursor, you have to gently push on the red stick in a direction you want. Right-button and left-button are right below spacebar. For the middle button, it doesn't work as a standard middle button but it will works as a wheel by hold the button and using the red stick to scroll in whatever direction you want--two or eight directions depending on the program.
Sound normal to you, right? It is. However, the advantage of TrackPoint is the position itself. While the touchpad is below the keyboard, TrackPoint is on the keyboard. While you have to move your hand a bit to use touchpad, you don't have to move your hand at all using TrackPoint. Imagine typing and scrolling the page back and forth, you will see how pain it is when using touchpad but it's so easy to TrackPoint. For a Trackpad--Apple's stuff, they requires your 2 finger--mostly index and middle one which you have to move your whole hand--to scroll the page, but for TrackPoint you just use your thumb to hold the middle button and your index to control the direction; you don't even have to move your hand. That's easy! For more example, scrolling the page, you have to drag your finger from top to bottom many time 'til the end of page. Nonetheless, you don't have to move any part to use TrackPoint; you just gently press on the red stick, how convenient. That's the point why I prefer TrackPoint to mouse when I read stuffs; it's so smooth like using MicroGear™ Precision scroll wheel of Logitech in VX/MX series but better in term of controlling.
IMO, the real disadvantage of TrackPoint is when you are using programs like Photoshop, using a mouse is a way much better! I don't think you will find any cons of TrackPoint comparing to touchpad though. Also, I found that TrackPoint is creating for a regular work, not intending to make it very accurate, or fast in any way, so it does not give you a perfect experience when you are playing a game like shooting, or any requiring accuracy.
Another point is finger pain, it does happen but it probably the same as touchpad. In addition, by setting to highest sensitivity and using the soft rim--type of TrackPoint cap, I think you will use it comfortably by now.
For who you don't believe me, try it by yourself; you'll know what I'm talking about.
Types of TrackPoint Cap:
Classic Dome: The Classic Dome cap is for users who prefer the touch and feel of the cap traditionally associated with the TrackPoint.
Soft Dome: With a large, convex surface area and soft texturing, the Soft Dome cap provides a soft touch and feel.
Soft Rim: The large, concave design of the Soft Rim cap provides a completely different touch and feel and creates a mechanical advantage whereby less force is required for pointer motion.
Edited on Jan 23, 2008: Soft Rim really helps you use trackpoint easier and lesser effort. You should try ;-P and, then, be happier with this :-)