Well, sorry to say this but I don't think it's very good. The transmission distance is meant to be 70cm and I had the distance between the transmitter and the display unit at less than 50cm and it wasn't picking up the signal at all - and this was with fresh batteries and the magnet as close as possible to the sensor. I also tried using my friend's cordless 7 and got the same results. In the end I opened up the transmitter, found the coil and lengthened the wires from the circuit board to the coil and ran them externally up my fork and attached the coil to my handlebars right next to the transmitter, and even then it was unreliable! I wouldn't buy another one. For my next computer I'm gonna get a wired one, I think I will put up with the ugliness of wires all over my bike to have reliable performance.
Also I don't like the cordless 7's mounting system, with the zip ties and sticky pads - makes it a right pain to move around or adjust.
Having said all this, when it does work it works fine - the display is easy to read, the functions are helpful and it's not too finicky to use mid-ride. If they gave it a better mounting system and made the wireless feature reliable, it'd be a fine bit of kit.