I only have a couple of flat paddle-shaped foundation brushes and I don't use them for foundation- only to apply and blend concealer. It's a personal preference, of course, and has a lot more to do with the formulas I prefer and my application technique than with the brushes themselves. I like to buff my foundation (and sometimes stipple) rather than do a thin even coat. That said, I like the angled foundation brush from Le Metier de Beaute and find it indispensable, because no other brush has its flexibility and precision when it comes to narrow and hard-to-reach areas (mainly along the nose).
Le Metier de Beaute Angled Foundation Brush is flat, synthetic, super-soft and has a lot of give, to the point of floppiness. That's why I prefer not to use it on areas like my forehead, but love the way it curves and adjusts to apply foundation around the nose and chin. The brush works best with liquid foundations and tinted moisturizers. The angled bristles are also good for fixing and blending is you have a patchy heavier area and is great for mixing two or more formulas.
Like all Le Metier de Beaute brushes, the foundation brush has a shortish handle that makes it travel friendly. It feels sturdy in the hand and has yet to shed even one hair on my face. It's obviously well-made and quite original, so those who're past the basic stage of brush collecting would most likely find it unique and useful.
Bottom Line: good brush, very nice to have.
Le Metier de Beaute Angled Foundation Brush ($50) is available from Bergdorf Goodman, Neiman Marcus and Nordstrom (online only, but currently out of stock).
All photos are mine.