I'd looked at this one before, but didn't use it, because of an awkward interface.
This one was a major update, and yes, the interface is much better, putting what you need the most close to your fingers, but without getting in your way. I think they updated the brushes as well. At least, I don't remember seeing watercolor brushes on the older app.
But. The max size of the brushes is pretty paltry, even on my little phone. And the painting can be really laggy. And I don't mean that it takes a while for the watercolor to bleed - the color doesn't even appear until a ways after you've lifted your finger from the screen. And in the end, after less than thirty minutes of doodling, the app simply crashed and burned.
I tried the app on my tablet, but it was even worse. I got only ten minutes before it shut down, claiming that my trial period had ended.