Let me start by stating that the Visconti Homo Sapiens is the nicest pen I own, hands down. It's been on my "to covet" list for a while, and I decided to treat myself recently, as a reward for a promotion at work.
The body is constructed from a dense black material that is a combination of basaltic lava and resin. It is slightly hygroscopic, meaning that it will absorb a light amount of moisture, and it's easy to grip, so it's a pleasure to hold for longer writing sessions. The trim, including the spring-loaded clip, is constructed entirely from solid bronze, and appears to be developing a lovely patina as the days wear on. While the pen comes packed with a cleaning cloth for the bronze, I don't envision myself using it any time soon.
The Homo Sapiens comes with a new 23k palladium "dream touch" nib, which is available in EF, F, M, B, BB, and Stub widths. I purchased the EF nib, which is apparently considered a specialty item, so you may not be able to find it at all retailers.
Unfortunately, I ran into trouble with the nib when I first got the pen. When I pulled it out of the box for the first time, I noticed that the nib and feed were misaligned. It wrote, but the pen was fairly dry, was a bit of a hard starter, and felt scratchy, due to a lack of lubrication from the ink. Goldspot Pens, who I ordered the pen from, arranged for me to send it back to the distributor for a nib swap. They would have done it themselves, but since the EF nib is considered a specialty item, they didn't have any spares in-house.
When I got the pen back from the distributor, I was dismayed - it looked like the nib and feed were still slightly misaligned. I inked it up to test it, and was immediately relieved. Yes, the alignment still appears to be slightly off, but now the pen writes like a dream (living up to the "dream touch" moniker). It has become a wet writer, and it simply glides across the surface of the page.
On Rhodia paper, the EF nib produces a line very similar to the gold EF nib on my Lamy 2000. However, the extra ink it puts down results in a much darker line; both writing samples above were written with Diamine Imperial Purple, and the Visconti is clearly darker. On more absorbent papers, like that in a Moleskine cahier, the line ends up being somewhat thicker - acting more like a fine nib.
The Homo Sapiens uses a vacuum power filler that's made from titanium. While I have heard other people complain that it doesn't draw much ink, I haven't had any trouble with it. It is definitely a bit trickier to get the maximum fill from this pen than one with a piston fill mechanism, but once you get the hang of it, it works quite well.