I've been lucky enough to score several samples of this, ranging from sachets to 4.11 ml deluxe samples. I've used it happily and would consider purchasing if I were in the habit of needing primer more often.
I love the packaging on these - the glass jar has a spatula in the lid so you can scoop out what you need - this allows you to scrape the sides which is great!
The primer is a stark white, but that disappears on your skin, leaving behind a smooth, balanced canvas on which to create a makeup look.
I don't feel that this necessarily makes the makeup last longer on it's own, but certainly makes a look smoother and more even. Having an SPF in is an awesome extra layer of security as well.
It's pricey, which is why i've not bought one (that and the myriad samples and things i have to use up, which takes ages because i don't always use primer) but I'd definitely consider it if I needed primer more often
I use this primer on my skin even when Im not wearing foundation, as it really does make the skin look THAT GOOD. It slides onto the skin really well and a little goes a long way. When Im wanting to look like a dewy youthful goddess this is the primer that I use under my foundation.