I have never used a primer before, so I tried the e.l.f primer as a starter because of the price (only $6). The gel feels like silicone and I use only one pump to cover my whole face.
The primer makes my face really smooth (seriously like silk) and makes applying pressed powder a lot easier e.g. it spreads across my face more smoothly and evenly. It also makes my powder last a lot longer during the day.
I started using the primer with BB Cream and pressed powder. But I feel like it's a bit much with the BB cream as well, so I use the primer with powder when I am going for a more natural look.
Unfortunately I am not a fan of the smell (chemically) but that is covered up by the smell of pressed powder/foundation. I also don't really think it helps with enlarged pores and fine lines.
But for the price, it is definitely worth it if you are just looking to make applying makeup easier and make it last longer.
For a first time primer user this was pretty great! It smoothed out areas that I did have large pores making them less visible when my foundation was one. However I still had a problem with dry/flaky skin in some areas.
I have to say though it made my skin feel amazingly soft and smooth.
Tips: Only use a small bit as it does go a long way!