I maybe completely different from the masses but I absolutely love this company. All of my makeup is elf. It does completely depend on the person though. If you are used to expensive high end cosmetics you probably would think elf's products are garbage.
Their eye primer (the mineral line one or the newer $1 one) is really good. My shadows last from morning to night and I tend to have oily lids. The studio primer isn't the greatest. The new face primer they have is really good, I would compare it to smashbox's photo finish (I do have the photo finish which I rarely use).
Their shadows have good pigmentation. I did swatches of the dollar line and studio line on this thread:
http://forum.purseblog.com/make-up/swatch-thread-all-other-brands-544108.html
I have all of the mineral line shadows but haven't done swatches.
There cream duo shadows are great as bases.
I love their blushes because they add such a pretty sweep of color to your cheeks. I have all of the mineral blushes and all of the $1 ones.
Their studio brushes are nice IMO too. The studio kabuki is a brush I use everyday as well as the powder brush, blush brush. I don't use them exactly how they say though.
The eyeliners are not that bad. They have several different ones. The pencil liners do tug a little. The felt tip liners are great but after a while dry out (which is typical). The liquid liners have serious pigment. The mineral liners are creamy. They just came out with cream liners which I haven't tried.
I would say 99% of my makeup is elf. I don't work for them I just love them. For their prices you can't complain. They always have coupons too for 50% off or sometimes even up to 75% off. I got all my mineral shadows for 90 cents each. Like I said a lot of people might differ with me but too each his own.
Oh I forgot to add that their stuff is not really sample size. Some of the products are pretty big. IMO you wouldn't want a gigantic something that you don't use up and have to toss because of bacteria.