We had a great stay at Gareth's place and generally agree with the positive comments already made, I'll try to just add what may be useful in addition to what has already been said:
We're from Johannesburg and very security conscious, and while Cape Town is much safer, I was happy with the level of security in the house. I won't provide any specifics on a public forum, just to say I think the security spec was much higher than what is often found in houses being rented out.
We have two energetic boys, 3.5yrs and 2yrs - the house was well set up for them, the chairs and cots provided were of a good quality, the patio railing was high enough for them to enjoy watching every train go past but without me worrying about them, the stairs had gates top and bottom, no easy breakable items lying around.
The train was not loud enough to wake the boys which is a reason we chose this house over some of the houses in Kalk Bay / St James that are closer to the line.
We liked the location due to the elevation and views (you can see the sea on the other side of the peninsula through the valley), beautiful light and mountains and views into the distance which you may not get down in kalk Bay area. My personal view is there is a tradeoff between views from your patio and being able to take an easy stroll to the nearby restaurant etc, we spent a lot of time at the house and therefore chose the views. For us it was a drive in and drive out location but worked very well for all the activities in the area. A bit of traffic on that coastal road towards Muizenberg but not too bad.
So overall was a fantastic house, Gareth was an excellent host, and we would happily go back if doing another holiday in the area.