It is not something that generates heat, it maintains body temperature, you don't sweat, it isolates the ambient temperature at reasonable levels, not to wear it alone and go out in the snow. This undershirt, shirt+sweater, at 13°-16°C you're okay, if you want something better, go for a 70-dollar one if available and you're good, for its price, it's fine.

Good but it doesn't really catch my eye, it seems thin. Also, take a smaller size because in the size I got based on chest measurement, it is wide!

Comfortable and high-quality, it keeps me warm just like the more expensive thermal wear that I have from a mountaineering gear store

It is very good for thermal insulation and for polyester it allows the body to breathe well, while keeping you warm enough without sweating. I deduct one star because the fluffy feeling of the interior, although very nice in texture, fades and disappears after some washes