Shiseido Perfect Foundation Brush was introduced last summer, just when I thought I was all set with foundation brushes (famous last words). Shiseido's innovation was the the angle of this very dense flat-top brush, as well as the small size.
The bristles, which I assume to be synthetic, are tightly packed and very soft. This allows for comfortable and effective pushing product onto the skin, stippling and buffing. It's great for small areas and for dealing with curves and crevices. The small head can cause streaks if you only move it straight across the face, so do keep that mind. I find that a light touch works best with cream formulas while tinted moisturizers can take more buffing.
According to Shiseido, the Perfect Foundation brush is intended for use with almost any formula, including powder, with one exception: water-resistant foundations. I prefer not to use this brush with powders, as I find the coverage it gives too heavy. This leads us to the comparison with the newish Hakuhodo brushes, G552 to G557. The main difference and the reason why this Hakuhodo range is more versatile than the Shiseido brush is that they are actually duo-fiber. The Hakuhodo brushes are not as dense, for better and for worse, so despite the similar shape, they are all very different and the Shiseido brush is utterly unique.
Amy from Cafe Makeup reviewed Shiseido Perfect Foundation Brush last year and has some useful tips for getting it clean (I use Shu Uemura cleansing oil).
Bottom Line: Really nice to have.
Shiseido Perfect Foundation Brush ($30) is available at the counters and from sephora.com.