I had a phase a while back where my skin wasn't being particularly co-operative, and as such I would always wear a primer.  I'm actually trying to think what primers I used to use, and can't really remember - this should tell you what effect they had on my life!  Not much, really!  I know one was The Body Shop primer, which was  a bit meh tbh, I had no particular feelings towards it.  I have tried the L'oreal studio secrets one that comes in a teeeeeny weeny pot and is ridiculously expensive - I didn't like that one at all.  And Benefit That Gal - which I didn't really understand at all.  Why did I not like any primer I have so far tried?  None of the primers I had tried really did what they claimed to - to prolong the wear of make-up!  Lately I'd been seeing Philosophy's the Present doing the blog rounds, and thought to myself hmmmmmm I wonder if it's any good or if it's just a fad.  But then I saw a GossMakeupArtist vid where he basically said it's amazing you need it.  And then, as if fate was shining down on me, I came across the smaller size on a blogsale for about £2, and I was like yes!  It was meant to be. 
I have been using this most days, and I can tell you, I adore it.  My make up stays on for a full 12-15 hours, and looks almost perfect at the end of the day.  It works so well that when I was out the other day with a friend and they popped to the loo, came back and said to me 'Have you reapplied your make-up?'  Now that, to me, after about 8 hours of wear is amazing!  The primer smells lavender-esque.  I say lavender-'esque' because I don't like lavender, but this is quite nice.  On the GossMakeupArtist vid he did say that some people could experience a reaction when this primer comes into contact with the sun due to lavender, so be careful, and test it perhaps on a forearm before smooshing it all over your face!  It is a white soft creamy texture, and the back of the packaging tells you to make sure you wait 2 full minutes before you apply your make up, and I agree that this is how it works the best.  I apply it as the last step of my skincare - cleanse, tone, serum, moisturiser and SPF, then primer.  Would I repurchase?  Defos!
 Hope this was helpful,
Love A.x

Don't chase after the past,
Don't seek the future;
The past is gone,
The future hasn't come.
But see clearly on the spot
The object which is now,
While finding and living in
A still, unmoving state of mind.
- The Buddha