I wont bore you with how to install - lord knows there are enough instructions included in the kit.
OK - it took a couple of hours to fit, including beer breaks and swearing. Not too bad to fit, except the 'ring' part would not go over the hand grip.

The external size of the grip is 5cm -

the internal size of the ring is 48mm - so it wouldn't fit.
The problem is, if the ring does not fit snug up to the switch then the bar thingy will not reach.
So the only way I could get this fitted was to trim the end of the rubber grip.
I did clean it up a bit, but the ring covers it so no big deal. It's just if I ever take this off then I will have to buy new grips.
Once that was trimmed it all went together pretty easy.
Well, until I went to adjust the brake part. The rubber bumper is adjustable but has a lock nut. So I backed it off so I could adjust and at that point I heard the sound of it dropping onto the radiator cover, never to be seen again. So for now I have left it off until I can get another nut for it.
But now I have been able to adjust the lock to where I want it to be, it does the job. I will be getting a new nut for the brake thingy tonight as that is a must. You just don't get time to de-select the lock in a butt clenching moment.
I'm happy with the look, it doesn't intrude on the grip width too much and it operates the way it needs too.
Overall I am happy with it. Used it on the freeway and it was nice to be able to rest my right grip to flip off HD riders

(FYI - I still own 2 HD's)
Worth the money? I would say yes. The R3 needed a throttle thumbscrew at least, but they must have been asleep that day during the design.