I went to a bookstore to buy a replacement for my Parker pen and I saw next to the original Parker ones that cost 5 euros, these Schneider ones for 2 euros and I thought: wait, something is going on here.
I see "made in Germany" and half the price compared to the French Parker ones, how bad can they be?

Well, they are just fine. I can't tell any difference in the smoothness and I use them interchangeably.
The shade of blue is a bit different, lighter, as shown in the photos.

At half the price compared to Parker, it's simply the right choice.
CAUTION: as a child mentioned below, it doesn't work properly in a Parker Jotter but only in a Parker with a twist mechanism.

I will come back regarding their lifespan when they are about to run out.

I expected it to be much better. A replacement at half its price is better. If you don't write for 10-15 minutes, the tip dries out and you have to draw a line of about 2cm to get it back. The color is nice too. It doesn't have the smoothness that cheaper replacements have. Its writing is average, nothing special. Just okay. For me, it's not worth the €1.40 I paid for it.

It was purchased to fit a Parker pen. It does not work properly in a Parker Jotter (classic click mechanism at the top) because it is a few millimeters shorter than the genuine one. It works fine in a Parker Sonnet (twist mechanism). The color is towards light blue. I also had difficulty starting the writing (dry tip). I can't say it's not worth the price of around €1, but I expected better quality considering it is a branded product and has competition.