Wireless ones aren't worth the trouble. They're too susceptible to interference from traffic-light sensor loops in the street, high-tension power lines, heart-rate monitors, etc..
We have some Avocet 25's in our large family fleet of bikes, and the ones they made in Taiwan were good, but the ones we got after they started making them in China needed frequent fixing, whether for cracked solder at the contacts, bad buttons, water getting into the sensor, etc..
When I researched the computers on the market in an effort to decide what the next few we would buy would be, I found in the owner reviews that there was a lot of dissatisfaction with cycle computers-- more than probably any other part of a bike. The Cateye Mity-8 and related ones scored well however.
We have several of the Cateye Mity-8 which is similar to the Astrale-8 mentioned above but instead of cadence it has two trip odometers. So far the Mity-8's have been totally reliable, easy to use, and have the functions we want. The oldest one is going on three years with the original battery. If you keep records of your overall odometer distance and the battery goes dead, when you put the new one in you can enter the odometer value and pick up where you left off instead of starting over at zero.
This message was edited by whittierider on 2-29-08 @ 8:01 PM