I have tried A LOT of ELF products. These are my thoughts on some of them;
The studio blushes are amazing! Great texture and very pigmented. They have a really large selection of colors too. I love the studio packaging as well. It is very simple a sleek like NARS. The regular line blushes kind of suck. At least IMO. I have tried a couple of them and they are really powdery and when applied they go on kind of spotty. The packaging looks cheap and ugly and you don't get much product. For just $2 more the studio blushes are such a better deal.
I LOVE the Studio and Mineral brushes. I like a few of the regular line brushes too but only the eye brushes. The regular line face brushes are kind of scratchy and don't work as well as the other lines. I LOVE the Studio Powder brush! It is $3 and works amazingly well for powder and liquid/cream foundations. I have 2 of them. The Studio Stippling brush is great too!
The eyelid primer is pretty good. It is nothing special but it does it's job. It doesn't work as well for people with really oily lids I have found. The lip primer/plumper duo is crap. The plumper smells like cinnamon, which is nice, but it doesn't plump my lips. The primer is nasty and it's like rubbing a drying stick concealer on your lips.
The liquid lipsticks are nice. They are more like lipgloss. The Cherry Tart color is my favorite. It is a really pretty red color but isn't an over powering red. It's a great color for people who are wanting to try out a red or aren't really into powerful lips.
The lip stains are ok. I like some of the colors they offer but it doesn't really stain my lips the way I want it to. I have to re-apply too often.
I adore the pink handled lash curler. It is the best lash curler I have EVER owned. The black handled one is not as good for some reason.
The liquid liner is ok. The black liquid liner is the best. The other colors I tried are usually a little too watery or too thick.
I like the palettes they offer. Like their Beauty Look Books. I have 2 of the beauty encyclopedias and one I really like and the other is kind of half and half. The large palettes are a great value! You can get them for between $5 and $10 and make great presents! I bought a lot of ELF for friends and family along with Wet n Wild products.
I have tried a lot of other stuff but these are the things I can remember the most. So all in all I find ELF to be a bit hit and miss. The studio line is definitely better than the regular line and is an amazing deal. I find most of my ELF products come from Meijer or Big Lots. Target has stuff sometimes but they tend to only come out around Christmas.