Is the Pentel Aquash water brush pen worth it?
I am also a novice with watercolor. The brush pens are pleasant to work with, especially if you have more control over your application with pens over traditional watercolor brushes. You can determine how much water should be used with pressure, and also use pressure to quickly clean pigment off the brush tip. I personally use the Ohuhu water brush pens, myself, but even then some traditional brushes will be needed. For example, I did a quick cactus with only one brush pen. This particular brush did not have a fine enough tip to properly do the needles as  I would have liked. So, as a beginner you will likely want to mix and match brush pens and traditional brushes. Brush pens can be fairly cheap, and the ones that come with an end cap are quite nice for traveling with!