My mother uses Jane Iredale, and I think it's fantastic. Not only is it good for the skin, but it goes on so nice and smooth, and the coverage is heavier, even with very little makeup! My mom has broken capillaries, and the J.I. foundation blends and covers it so well, and she doesn't need to build it up or anything!
I think the only "big" thing is that it has to match your skin color. I have heard that it's a little bit more difficult to match the JI foundations to your skin color, but if you can, then it's absolutely wonderful!