This is the first concealer I've bought and I love it!

I'm not quite sure what shade I am in terms of MAC foundations (or any foundation at all actually, I don't really wear it) but I use the shade 03 - Light for this concealer. I really did my research before I bought it - I'd read LOTS of reviews comparing it to MAC Studio Finish Concealer (but for a fraction of the price!) so I thought I would give it a go....and I'm SO happy I did :D

I use it primarily to cover up dark circles and I have to say I think it's done a great job! Shade 03 - Light has a slight peachy-orangey tone to it, so it's perfect for covering up my blueish-purplish undereye circles. Its pigmentation is not the strongest I know is available - it has a medium pigmentation - but after I've applied it, it literally looks as though I've airbrushed the skin in that area.

This product can do wonders for you - if you know how to apply it correctly. First, use your fingers to spread it across the skin, but after you've placed it, WAIT for a little bit to let it set. This makes it more pigmented for some reason (I have no idea why but it does) and means that you have to use less product to cover your trouble areas. After spreading it across your skin and blending it in (which is a dream to do, it's an incredibly creamy product that spreads really easily if you heat it up a bit before hand or through applying it with your fingers), MAKE SURE TO SET IT WITH A POWDER OF SOME SORT. I used to apply it onto my skin with my fingers and blend straight away, WITHOUT setting it, but by the end of the day, it just looked cakey and had a gray cast to it and horrible. Setting it with a powder makes sure it stays in place all day and doesn't melt off your face. After doing this, the concealer looks just as good at the end of the day as it did when I first applied it in the morning :)

I bought the jar I have for about $6 (I think?) and it's lasted forever so I know it's really good bang for my buck.

I've never tried using it to cover acne spots or blemishes though, so I'm not quite sure how it works for that. But if you're looking for a good under eye concealer, this is it! :)

i got mine for $5 on cherryculture.com (shade 03 light)
i really like the texture and consistency of this concealer. it covers fairly flawlessly but isn't difficult to work with. i don't usually have much of a creasing problem, but it doesn't work all too well with my dry skin. i like the look of the packaging but having to stick my finger in it annoys me because my acrylics get in the way. i usually pat it on with a brush first and then blend in with my finger.
here's a swatch:
http://tinypic.com/view.php?pic=2igohlk&s=5

I bought this concealer off of cherryculture.com- link: http://www.cherryculture.com/cosmetics/makeup/nyx/nyx-concealer-jar/16597&cat=289&page=2
for US$4.25 but it is listed on Nyx's website for US$5.50. (as a side note, I don't recommend cherryculture, it was cheap but it took them about a million years for them to mail me my things and the shipping costs were $$$$$)

I wasn't expected much from this concealer and it was my first time using a pot concealer like this but I actually really loved it. I used it underneath my foundation for blemishes and it completely covered them. Good pigmentation, good shades and the right coverage. It is thick but not cakey and isn't plastered on your skin. I have trouble finding the concealer in stores here in Toronto, but if you do- highly recommend trying it out. (also- definitely use a concealer brush with these pots!!!)