I have used this for maybe 4 years now and done several thousand miles and the only things i've had to replace apart from the Batteries is the magnet that goes on the front wheel. Any magnet will do and i got mine from Halfords for £2.99 which is made from metal and just screws on where as the original is metal with plastic.

Batteries:
2x CR2032 button style (1 for computer and 1 for sensor)

Fitting:
The sensor is fitted with a couple of cable ties around the fork.
Magnet secures easily with screw driver
Computer mount is fitted with 2 cable ties

Functions:
Speed, Max Speed, Distance, Odometer and Clock only thing for me that it's missing is average speed

Ease of setup:
There are 2 small buttons on the back you need to push a pen or something into unless you have small fingers.
1 is set and the other AC. You press the big button (mode) on front of the computer to choose either mph or km then press set, then choose your tyre size by looking at the chart which comes with the computer.
Setting the clock is just as easy, follow the detailed instructions.
That's it now you place it in the holder where it will click then from now on you have just one button to wory about! The big one called mode which toggles throughout the functions and acts as a reset for the current journey when held in for 2 seconds.

Would i recommend it?
Yes it's a great computer for anyone starting out to distance cycling or someone who needs to know how far and fast they have gone but just lacks average speed function so i'm moving up to one that includes that but will still be Cateye.