I really like their brushes. I only have a few, but their EB13 is a great synthetic tapered brush that can be used for many functions.
For the longest time, I refused to buy sigma brushes because I just thought they were overrated and everyone raved about them. I finally bought the Sigmax collection and I although I like the F80, I never reach for that set! I have reached for it a total of 3 times and it's been almost a year. Go figure.
I bought their E40 and it shed like crazy, I couldn't believe it! I called and they replaced it, but it still sheds quite a bit. I'm sticking to my handy 130 brush, my RT brushes and my 208, 224, 217, 239, etc...I will say that I like their small tapered highlighting brush though.