There are definite pros and cons to Revlon Colorstay Foundation.
Pros: I have oily skin that's a bit red and blotchy due to severe acne that I suffered from years ago, so I look for foundations that provide medium to full coverage and have a matte finish. Colorstay has one of the nicest finishes I've ever encountered: it's smooth, even, and velvety, and doesn't emphasize my large pores or settle into themm The colour Buff matches my light skin well and doesn't have any pink or orange tone to it. And this foundation's claims of not rubbing off and staying put are very true...which brings me to...
Cons: This foundation is very tricky to apply. You can't use your fingers to blend it; a sponge is necessary (I found that a sponge-on-a-stick type brush worked OK, but even then, it was very difficult to blend). It sets very quickly, so if you make a mistake and overapply, you're out of luck, although a bit of powder can camouflage application errors. Finally, this makeup is rather difficult to wash off. After a few wipes with a baby wipe, scrubbing with Noxzema and a washcloth, and going over my face with toner, I was STILL picking up traces of makeup.
Another minor gripe: I hate glass bottles for foundation, and this one has a particularly wide opening, so it's very easy to pour out too much. A pump or a squeeze tube would be much more convenient!
Conclusion: Although I love the way it looks, Revlon Colorstay Foundation is not worth the trouble for everyday wear. I'll save it for special occasions.