I have had them for 3 months and the glasses are perfect.
They haven't gotten wet and I even put them in the dishwasher.
I am completely satisfied!!

Three out of four cups got wet, I do not recommend them.

They are beautiful, practical with good capacity. They lose stars because 3 out of the 4 caught moisture in the intermediate wall from the first days. If I were to rate based on emotional criteria, I would give one star. However, I will hold back because objectively, they still do their job. Even if the drink you put inside is boiling, you don't burn yourself.
Solutions I found online include "baking" the cup for an hour in the oven at a temperature just above 100 degrees, submerging the cup in a container of warm water to see where it "leaks" and then removing the water with a syringe, placing the cup in a bowl of rice to absorb the water, and finally, invoking Cthulhu. The last one seems more likely to me; I am not going to sit and play with ovens and rice for cups that were purchased for €7 each. The least I would expect is for them not to catch moisture.

--- 16/09/2023 ---
Eventually, the fourth cup caught moisture too. Expected. The good thing is that they still do their job. You put boiling water inside, and your hand is not even lukewarm. Aesthetically, however, they are a disaster. Like double-glazed windows that have caught salts from the steam and cannot be cleaned at all.

--- 08/12/2024 ---
For the record, the two that remained unbroken have also caught regular water in the middle. You wash them, dry them, and see inside two or three large, plump drops moving from the bottom to the rim, depending on where gravity takes them.

Amazing cups, sturdy, high quality! They attract attention and everyone admires them with any drink they have inside!

Good, honest, and as expected. Just very expensive and not very refined in the details for such an expensive set. Overall though, good.