The modern Kaweco Sport pen is a workhorse: it's pocket-sized, durably built, and (generally) affordable enough that you aren't overly worried to stuff it in your pocket and take it on the road with you for work, travel, or just knocking around town. The popularity of the Sport is such that Kaweco has developed several lines, the "classic" plastic sport pen, the AL Sport, and the AC Sport Carbon Fiber edition. This review focuses on the AL Sport, in black, which retails for around $75, per my last market check.
The Kaweco AL Sport is a very well-built fountain pen for the price. The body of the pen is made from machined aluminum. It is sturdy enough, but the pen will develop a patina and scratches and dings with long-term use, especially if you use this pen as a true EDC "pocket pen" and carry it around in your pocket with keys, coins, etc. Most people don't mind this, as they feel that it adds to the aesthetic value of the pen. In fact, Kaweco recently released a "stonewashed" version of the AL Sport, which seems to be a "pre-aged" version of the regular AL Sport with the aluminum coating worn off. I have not seen this pen offered by U.S. retailers. The Kaweco Sport line takes international-sized cartridges, and works best as a cartridge pen, in my opinion. There is a squeeze converter option, but I have had mixed success in getting an adequate ink supply into the converter to last me through a full day, so I either use the cartridges with Kaweco's excellent ink or refill empty cartridges with a syringe.
The pen closes to true pocket size, but once opened and posted it is a full-size writer. I actually prefer the AL Sport as a daily carry over the Lilliput, for this reason. The Lilliput is great, and a neat little pen, but it's so small as to border on "novelty" territory. The AL Sport is still small enough to fit comfortably into your pants or jeans pocket. You can purchase a clip, but I've found that the Kaweco clips tend to be too tight to use on my shirt pocket without risking a tear. Plus, I don't like spoiling the streamlined look of the unadorned pen itself.
Kaweco's nibs are well-made, functional stainless steel nibs made by Bock. My extra-fine nib may not be the world's smoothest writer, but it doesn't skip and actually leaves a true extra-fine line, which is rare with German-made nibs. Nibs in the Sport line are interchangeable, so you can purchase replacements. The nibs come in sizes EF through BB.
I love this pen. I purchased it from jetpens.com about a year ago, and its been in my rotation ever since. I'm eyeing the carbon-fiber version (in red), but have not been able to make myself take the plunge. For an excellent review of that version of the Sport, check out Bob's review at My Pen Needs Ink.
N.B.: I've attached a handwritten version of this review in the gallery below. The ink used is J. Herbin's Vert Empire, which does not scan very well and comes out more grey than the grey-green. I've also included a photograph that's a more accurate reflection of the ink's true color.