people asked a lot of questions that i think this will answer. this is all based on my own experience and skin...
UDPP vs. MAC PAINT....(not paint pots, were talking about the tubes)
#1 i walk to work and wind makes my eyes water and my shadow at outer corners of my eyes gets ruined.
UDPP-- screwed. you cant let it just dry because youll have a circle of blurred shadow, if you dab it to get the water off, all of the makeup is gone. if you try to rub the shadow to drag it over and blend it into the now blank spot, the shadow will either come off in flakes, or just rub off! all you can do is wipe the corners off and put more primer and more shadow on.
MAC PAINT--when i dab the corners of my eye, pretty much only the water comes off and possibly a teeny bit of color. if my eyes were extra watery and a noticeable amount of color came off, once my eyes have stopped watering, i can lightly rub my shadow with a finger to drag it over and blend it and it looks great.
#2 packaging & application (i blend both with my finger)
UDPP--tube with doe foot wand applicator. i have to dip in in, repeatedly to get enough product out because theres like a DOT of it on the tip each time you pull it out. once you saw it in half and put it into another container, it gradually gets thicker and thicker which i think feels gross on my lids. it goes on like friggin clay. heavy! but even then, it still works. its hard for me to remember a lot about how it worked when it was in the original tube because so much product was scooped out when i sawed it in half- that its been out of the tube for longer than it was IN the tube.
MAC PAINT--small metalish paint tube with a tiny cap. cap is easily fumbleable especially when youre franticly trying to screw it back on before more paint squeezes out on its own. this is a constant problem, until you get used to how much pressure is needed in order to get the amount you want or else youll waste it all very quickly. very light consistency, goes on very smooth, weightless on your lids. product never dries up because of tight cap, and all of the product is able to be easily used without cutting things in half!
both products grab color well, although i think the mac paint is more grabby. because the paint is thinner, its easier to blend it into skin at the edges. paint also comes in a very light beige which matches my skin tone exactly so its idiot proof to apply and blend. someone asked if paint makes your skin look scaley. yes i believe it does, mainly if the eyeshadow has shimmer in it. i personally think it looks kinda awesome though especially with blues or greens, very mermaid. udpp does it sometimes as well...only with udpp it looks more like crust than scales! YUCK. i forgot to mention, the mac paint only leaves you about 1-2- minutes to put your shadow on before it is dry...so if you are the type of person who takes a long time doing your eyes, youd probably like the udpp because it stays tacky longer (at least my gross thick udpp does)
your a big girl now, you dont need to buy products which require you to saw containers in half. shell out the extra $5 and buy mac paint, you wont regret it!