Extremely durable and comfortable. Keep in mind that we are talking about close-toed sandals with all that entails. Before you get them, you need to know that they are close-toed and what limitations and advantages that entails.

Very hard, I would not recommend it for someone who is not very experienced and knows how to do the movement correctly

Excellent for exercise. The only drawback is that after some time, it starts to release the elastic and darken the nails.

+1 to everything Yannis_Tholoulis said. Not suitable for snorkeling, minimal thrust for the effort someone puts in. It's better to choose something else for these activities.

I have had them for 2-3 summers. Hard and probably short fin. Hard body in general. In seawater (with strong waves) they do not contribute significantly to movement, therefore also to training (freestyle). They almost stay/find on the surface of the sea.
I don't know if they offer anything more in a swimming pool. I really understood how much time I wasted with these fins
when I bought a second pair, of the same value, from another company with a soft flexible fin.

Very good flip-flops. Good fit on the foot and made of good plastic. They don't tire you out while swimming but they also don't give you a lot of propulsion.

Tight fit and good, you don't even notice it when it gets wet. It doesn't tire the feet when using them. Good plastic and hard