I purchased the VELO-5 at my local bike shop about a week ago. I had had a computer in the past on a different bike; I don't remember the model, but I bought it at Walmart for $10 or so. I was hoping that a major bicycle accessories company would have a slightly more reliable product.
When I opened the package, I was mildly disappointed; the computer, sensor, and wire were mounted via plastic cinch strips, instead of proper mounting brackets, like the cheap computer I'd last used. Nevertheless, I installed it as indicated in the directions; I had no trouble with the sensor and computer unit, but when I attempted to install the spoke-mounted magnet I immediately stripped the threads on the cheap plastic "bolt" that holds it in place. I wasn't using a pair of pliers, just my fingers. In the end I was able to get it reasonably secure, until I started riding and it immediately slide on the spoke to the rim and the sensor couldn't pick it up. After a few miles, the magnet loosened itself up and flew off the wheel into the woods.
Luckily, I discovered I still had the all-metal magnet/bolt from the old computer I had, and put that on. Worked like a charm.
I wouldn't suggest buying the Velo-5 unless you already have a spoke-mounted magnet lying around that you can use. The computer itself works great; it's accurate, even at low speeds (a major problem for the cheapo Kmart computer I had), and the single-button operation couldn't be simpler to use. If they'd start using a metal backer on the magnet, I'd give it 5 stars.