I have most of the full-sized brushes from Smashbox, and I've got to say that the quality is decent.
The ones that I've got are:
Arched Eyeliner Brush 21
Fan Brush 22
Face & Body Brush 19
Concealer Brush 4
Foundation Brush 13
Crease Brush 10
Blush Brush 16
Blending Brush 3
Powder Brush 1
Definer Brush 15
And brush 11, which I think they've discontinued, but it's a fluffly angled brush that I use sometimes to put on my browbone highlight.
The brushes are pretty good, not as good as MAC, in my opinion, but they apply makeup quite well.
Another thing is that MAC has more brushes for sure.
Something I noticed is that the Face & Body brush #19 sheds A LOT. It's really nice to apply powder or to buff away extra blush when I OD on blush, but I've had it for over a year now, and everytime I wash it, it STILL sheds. And sometimes when I'm putting on my powder founation, I get little bristles all oer my face and shirt. It's a lovely brush, but my only problem with it is that it sheds too much!
And if anyone wants an in-depth review of any of the brushes listed, let me know.