Let's start:
Positives
1. Relatively sturdy. However, I've only had it for 3 days, so I might come back after a few months of use.
2. Very affordable.
Negatives
1. There is no eraser on the back. NECESSARY for this type of pencil. The bad thing is that I called the store where I ordered it from and they told me it has one. Well, IT DOESN'T. I'm writing it in capital letters to emphasize it.
2. The way to insert the tips is unfamiliar. You have to unscrew the lower part and press the button from the top to open the wings of the tip and carefully pass it underneath. I didn't know that either.
Conclusion
If I knew the negatives, I wouldn't have bought it. I would prefer to spend another 20€ and buy another one. I bought many pieces as gifts for our Company, but in the end, I was disappointed.

Anyway, if you're looking for something very affordable, it seems to do the job it's intended for.
Good design, whether on paper or on concrete, brick, plasterboard, etc. :)