I got this design because I am really wary of the windscreen sucker-type coming off, and the cup-holder type is too expensive. I have a 2002 Seat Ibiza and the air vents are circular and recessed quite a lot. Also, the vanes turned out to be really deep, over 2cm. This is something to be aware of - it would have been a fatal flaw for this holder as the clips provided could not go in far enough and hook onto a vane. Luckily, by removing the knob that opens and shuts the vent I gained access to the middle vane, which was for some reason half the depth of the other ones. The holder clipped onto that perfectly. It is now very stable, and the grip on my iPhone (in a thick plastic case!) is great, both vertically and horizontally. The side clamps expand up and down so you can always fit in the charging lead (if in horizontal position). It blends into the dashboard nicely, and is next to the steering wheel, in my field of vision, and easy to quickly tap with the left hand if necessary.
The only issue I'm seeing is removing the clips from the vent vane in future, since they hook on. I shouldn't need to think about it for a while though, and with a bit of fiddling I think it should be OK (the whole front comes off, leaving a small back plate attached to the vent, so I should be able to get in there with a thin screwdriver if necessary).