I like the odometer because it makes it easy to keep track of when I need to change my chain (every 1000-1500 miles), and how old in miles other parts on my bike are. My first odometer was walmart $12 and I was pretty upset when it went braindead at ~3700, and again at ~4000. I replaced it with something from Nashbar, not the cheapest but nothing expensive, because I had better things to spend my money on, like new drivetrain and shifters and brakes. All I can say is, if you have to get super cheap walmart odometer, plan to replace it in less than a year, and keep an eye on the total miles so you know what to set the new odometer to when the cheap one fails.