A few weeks ago I did a demo at work trying out the Pentel Pocket Brush Pen and the Pentel Hybrid Technica fine point pens. I drew these big cats using a National Geographic poster as a reference. Since I was just experimenting, I didn't pencil anything first.
Snow leopard. Rawr.
Leopard. I deliberately did this one with few outlines, trying to convey the contours with the spots.
The tiger in the original photo really did look this morose. It must have been having a bad day.
The above were all drawn with the Pocket Brush Pen on smooth Copic paper. The PBP is a smaller version of the well-known Pentel Color Brush pen; it's the size of a normal pen, and refillable with cartridges. Like its bigger sibling, it has actual nylon bristles (rather than a felt nib) and a nice inky feel to it, much like using a real brush dipped in ink. If you press hard, you can get a scratchy drybrush texture (depending on the paper), which surprised me, as ink pens don't tend to deliver enough liquid to smear around like that (cf. for instance the loose dark areas around the snow leopard).
For me, this brush pen wasn't a keeper because it just didn't give enough resilience and control in the middle line weights; it felt too soft and mushy compared to the type of brush I like. (The only brush pen I've liked so far is the Pitt pen, whose springy felt nib gives a surprisingly good mimic of an actual sable brush, for juicy thick lines or tiny thin ones.) But I can see how someone with a looser, more sumi style would enjoy the Pentel, and of course it would be ideal for Asian calligraphy. It's also handy if you want to quickly color in a large area of black.
And then there's the sort of dragony critter I draw when I can't think of what to draw. I used both pens on this, on vellum finish bristol which, despite being fairly smooth, gives the lines more texture. The broken lines of the belly and tail are an example of unintentional drybrush dragging; I did this drawing first and then switched to the smoother paper, but the effect could be used deliberately.
For this lion I mostly used the Hybrid Technica, using the PBP only where I needed a dense black area. The Hybrid Technica comes in four sizes, all of them EXTREMELY TINY (I used 04 and 06). If you like cross-hatching ("For me, drawing is just an excuse to do some cross-hatching" -R. Crumb), which I certainly do, you will enjoy this pen. I also like that it has a metal tip rather than a felt tip in a small metal cylinder, like Pigma microns. For some reason my hand angle has never gotten along with the micron-style nib; also, the tiny felts can be easily bent or worn down. The Technica's metal tip delivers satisfyingly black ink like a teensy rollerball, not the unsatisfying grey of ballpoint. The only thing the Technica lacked for me was the ability to scribble out a dense black the way one can with a rollerball such as my favorite drawing pen, the Tombow Object. Once you start to layer lines densely on top of each other, the Technica's metal tip starts to scratch at the ink like a ballpoint. It's definitely a pen I would like to own and use again; I'd just use another tool for dense black.