This week I tried out the Sensu Brush on my favorite art app for the iPad Pro - Procreate (see review of this here).
Overall, the Sensu Brush generously gives off the feeling of using a real roundbrush on a surface. Using the Sensu Brush on an iPad feels like watercoloring, or like brushing a thin wash of ink over smooth paper.
One of the biggest challenges with the iPad Pro + Apple Pencil setup for a visual artist is the lack of surface friction - the Sensu Brush helps overcome this. The bristles of the brush create a surface drag which mimics the convincing effort that goes into IRL painting.
A Sensu Brush next to an Apple Pencil
That said, pressure sensitivity goes missing from the Sensu Brush + Procreate. Touching the brush ever-so-lightly to the iPad Pro creates the same marking as touching down as hard as possible. This would make most art creation difficult if not impossible with the Sensu Brush if Procreate (and other art apps) didn't have opacity variance.
Imagine: A pressure sensitive tablet brush. I say 'Imagine' because this would be a very difficult piece of hardware to develop. I can't fathom how it would work with so many different endpoints in question. A painter's brush has at least 200 individual hairs to it - how one go about making each endpoint pressure-sensitive is a question far beyond me. And, I'm sure it would go far beyond the Sensu Brush's retail price of $40.00.
I'd recommend the Sensu Brush to artists when they need to relax and make full-opacity work, or when fiddling with opacity won't be a nightmare. If you're tired of needing to endlessly re-load your IRL brush or nib with medium again and again, the Sensu Brush provides a heavenly break.
Strangely enough, the Sensu Brush works well for inking a project due to the non-variance in opacity/lack of pressure sensitivity. It can be a little tricky to think of a brush as a pen-nib, but it works out after a few tries. It's also great for a rainy day when you just want to make color fields and get color on the screen as quickly as possible, and feel great while doing it.
More info: http://www.sensubrush.com/