You can run your finger around the iPod's famous click wheel fast to jet down to the W's and then slowly to pinpoint "What a Wonderful World."
But the Rio's thumb wheel has no such variable speed; it's four songs per turn, period. Working through any list longer than about 12 songs is an excruciating exercise.
you see the problem. Another extract takes the Creative Zen Micro to task:
[T]he iPod's wheel has been replaced by a touch-sensitive vertical strip. In theory it ought to offer variable speed scrolling, but in practice it's a sticky, balky nightmare. You'll find a similar lack of polish when you want to use the Zen Micro's hard drive to transport computer files (a terrific feature of the iPod and all of its rivals) and discover that you must tell the software in advance how much space you'll need for them. How could you know that ahead of time?
Who thinks this dreck up? Oh...that's right...engineers and marketeers.