I bought this about a month ago. It's the wired version, but for the money you can't go wrong. There's a single wire that runs from the "sharkfin" on the chainstay to the computer. Mine runs up the bottom of the down tube and is barely noticable. You are limited to the standard yellow CycleOps wired computer. So if you want to integrate with a Garmin or some such, you have to go wireless.

I started out with a Polar system that I bought used. Let me know if you're interested -- I'll let it go real cheap. The Polar power meter is a pain to install and setup, but works reasonably well.