Pros: Durability, Refill Quality
Solid & Low Key
After a couple months of moderate use of the SpacePen, I consider the instrument to be well built, producing a smooth and consistent line. The pen 's performance is unaffected when employing it upside-down as claimed, however I have not tried writing under water or on an oil marred surface with it, and therefore can't speak to those abilities.
The matte black exterior gives this SpacePen a "plastic-e" unremarkable appearance, not unlike a disposable Papermate. That attribute may help keep the pen on your desk longer.
Regardless, it's a steal at under $15 including shipping. Gotta love the KnifeCenter.