The Body
The Uni-ball Signo DX (UM-151) line have a good-sized barrel for those who don’t like thin barrels that often accompany micro tips. It’s very comfortable to hold and didn’t strain my hand after extensive writing.

I was a little bit disappointed that the grip was so small though. It is barely thicker than the barrel itself and stops short of the metal tip, leaving a little piece of plastic barrel between the two. Which, incidentally, is where my fingertips actually grip when I’m writing. However, it has more grip than other micro tip pens (such as the Pilot Hi-Tec C line) which have no rubberized grip at all.

Note the plastic space between metal tip and rubber grip
Despite being a fairly thin tip at 0.38 mm, comparable to the 0.3mm Pilot Hi-Tec C, I didn’t have a problem with the writing. Ink flow was very smooth and, perhaps because I’m used to writing with fine nibs, I did not feel the nib was scratchy. I have a friend who tried it, and she commented it was a bit scratchy for her - but then she usually writes with 0.7 mm nibs and larger.
The nib is also well built. As usual, I performed my highly advanced scientific test of nib strength by violently tapping the nib on my notebook (in this case, I have stuck with my trusty Quo Vadis Habana). The nib held up well to my abuse and again, I suggest you don’t try my HASTONS (highly advanced scientific test of nib strength) at home. Unless you’re prepared to lose a pen or two. Even with heavy writing, the nib held up well. I did not have any problems with ink blobbing on the ends, which results in ink blobs - often a problem with cheaper pens. Personally, though I love the Pilot Hi-Tec C line, I think the 0.38 mm nib feels sturdier than Pilot’s 0.3 mm, or even the 0.4 mm nib.
From left to right: Pentel Slicci 0.7 mm in pink, Pilot Hi-Tec C 0.5 mm in pink, Pilot Hi-Tec C 0.4 mm in pink, Pilot Hi-Tec C 0.3 mm in pink, Uni-ball Signo DX 0.38 mm in blue.
The Ink
It’s hard to drool over thick, bold lines of ink when your nib is only 0.38 mm. But from the color of the ink through the barrel, it’s pretty nice. And the tiny little 0.38 mm lines left by the pen are pretty solid. The blue, blue-black, and bordeaux-black that I tried out are all very sharp but obviously are not brilliant, happy colors. They are quite professional looking, if you are seeking a gel ink pen for work. Or for signing important documents.
The ink dried pretty quickly in my test. I made a scribble and with no time to dry, I smeared my finger across it (another highly advanced scientific test). Clairefontaine paper is very smooth and usually, all inks take a few seconds longer to dry.
So far, the ink is lasting me quite awhile. The ink cartridge is quite wide and because the nib is so thin, it doesn’t use up ink very quickly. This is great for those of us who want a pen that lasts a long time. Not so great for those who have OCD and obsessively monitor their ink levels as they write with excitement so they can proudly use a pen from start to finish without their ADD taking over (not me).
Eco-Conscious?
Fortunately, these pens are refillable. However, like most refillable gel ink pens, the refills only come in select colors. Unless you’re really into black, blue, blue-black, and red, you’re out of luck. Hopefully Uni-ball will add some more colors to their available refills.
Price
JetPens - $2.25 each
Jetpens Refills - $1.20 each
Overall
I really like the Uni-ball Signo DX line. It’s a great pen for anyone who is curious about the micro tip pen world but are hesitant to try a softer nib in fears of breaking it. The pen is really nice looking and can easily pass for an elegant work pen. Not bad for $2.25, but even better that it's refillable!