been using the cateye velo wireless for years and never had any issues with it. it's been through some harsh weather too, rain and snow, and sticks and stuff, some surface scratches from debris but it still works fine. was simple to install and set up.
It's functions are limited but it's got basic stuff like current speed, average speed, a tripometer and odometer. I guess the only thing i've noticed is that it stops working if you ride near any serious power lines, but it picks right back up once you're clear.