I use these pens virtually everyday. They are fine tip (0.4 mm) which means I can write very small if I want to. The variety of colors is great. I own the wallet set of 10 and I always have a big enough variety of colors to accomplish what I need to.
As a student, I find these pens great for studying. They almost never smudge, and making small notes in textbooks, study guides, and lecture outlines is very easy.
I live in a dry region and some pens dry up unreasonably fast, but not these pens. Even with using them basically everyday, I have not had any of them start to run dry for the approximately 6 month duration I've owned them.
As someone who is not particularly gentle on my pens, I can say these will stand up to a beating. Even though I have stepped on them and accidentally tried to bend the caps, none of the pens have warped or shown signs of breaking. I particularly like the boxy shape of the pens. It makes them a bit stronger.
The main body of the pens are yellow/orange which makes them harder to loose or leave with your friend. I find it useful to have items that stand out, particularly when I use them at work and they may pass through other people's hands in a meeting.
The set of ten come in a nice plastic case which has also stood up to reasonable abuse. The case is designed so that you can fold back the lid and prop the whole set up for easier access. I do not typically use the box propped up, but I have kept the pens in this case. The part of the lid which bends has shown some wear, but it is still functioning as intended.
Sometimes these pens can be a little annoying if you need to write something larger. This isn't really a fault of the pen since they are designed to work best for small things, but if you anticipate needing to write larger, I would have some other pens at hand.
Given the durability of both the pens and the case, these pens are very reasonably priced. You'll invest in a strong, long-lasting pen when you purchase these.