EDIT 01-31-09: Sadly, I've found that if I want to put eyeshadow all over my lid (I'm a n00b lol), UDPP doesn't quite cut it alone. It only prevents creasing for 5-6 hours (which you know, is much better than like 1 but it's still kind of disappointing). I have to put Painterly paint pot over this to get it to last 8-9 hours, which is an annoying extra step, but Painterly does nothing for me by itself, so I'll keep using both.
I've been resisting buying this despite the cult following for a while now rationalizing that... I don't really wear eyeshadow.
Well, the reason I don't wear eyeshadow is that my tiny Asian eyelids get so greasy that any eyeshadow I put on them totally disappears after 2-3 hours (max). (That, and I don't really know how to do eye makeup.) However, I recently decided that I wanted to try eye makeup, and caved on this.
I love it! Sometimes I like to just put a swipe of EDM In the Garden along my lashline for a subtle, smokey lined effect and this made it last ALL day (8 hours) BEAUTIFULLY. It never would have guessed how much prettier eyeshadow looks using this a primer, but it really made all the color/iridescence of my eyeshadow pop on my lid.
I use just a touch of the doe foot applicator on each lid and pat/spread it on my eyelid. The stuff is pretty easy to work with and then I just let it set while I put on my blush. I have noticed that it really "grabs" pigment, so I have to be careful not to put shadow directly on it where I don't want it, otherwise it's basically impossible to blend/smear away unless I use a makeup remover, but I guess that's what makes it last so long. I know a lot of people who use this apply a wash of color all over it as a base first and I think that would work a lot better.
Rant rant gripe on the packaging... actually, quite frankly, I think it's quite a lot of product, so I don't think I'll be sawing open the tube anytime soon. And if I do need to, there are plenty of tuts online.