Very good quality!
The leather is a bit stiff, but it softens over time!!
Regarding the size, you may need to go one size down compared to your sports shoes!

As for the size, it is initially a bit tight at the front of the foot and hits the toe box (where the seam for the tongue is) but after 10 days of daily use, the leather softened quite a bit and it doesn't bother at all anymore. Personally, I wouldn't choose a larger size (I wear 45 and in sports shoes), and that's because it softens and opens up in a relatively short period of time.

On the official brand page for this specific model of leather, they say it is true to size and many suggest to take one size lower than your usual. I believe they are wrong. With a foot length of 30cm, I took the 46 which has a sole length of 30.5cm. It took me a long time to break them in. It took a quarter and three passes with neutral cream inside out. In the end, I wore them twice with three thick socks which gave them the right stretch. Now they are okay and I now wear them with extra anatomical insoles which I believe are necessary. They are nothing like the comfort that Martens had twenty years ago, they no longer support the arch. In no case for work and gardens, the yellow seam of the sole ripped at one point after a walk in a field. Overall, it is a very nice boot and as for the seam, it melts easily with a lighter and becomes one with the plastic. If I buy Martens again, it will be size 47.

I got my size (I wear 39) and they are generally wide. Maybe the 38 would have fit me better, but I will definitely wear them for many hours. I preferred them to be spacious because I will also wear them with thicker socks and sometimes add an insole. On the first day, I got hit high near the calf because I was only wearing tights. Their sole is good but heavy like a boot. They are something between a flat shoe and a traditional boot. They go well with everything, even with good trousers!