Not bad, as it does darken the background to comfortable levels. Unfortunately, it is extremely difficult to read the tertiary text in comment boxes and in the messenger boxes, and there is no option to change the color of this text.

Não é ruim, mas também não é bom
Tem que ser corrigido alguns Backgrounds

Looks pretty good on messenger, but on facebook the comment fields are white, as well as the chats. Seems like it needs an update.

Dark gradients don't look very good imo. Still, does what it says it does.