The other side of the coin noun phrase
Used to refer to the opposite aspect of a subject or a situation
I like wearing white clothes, but the other side of the coin is that they easily get dirty.
Sometimes, I get lonely when living alone but the other side of the coin is that I have amazing freedom.
Working as a freelancer gives you flexibility in work time, but the other side of the coin is that you don't have a stable salary.
Holding opposing opinions on an issue or in a situation
A person who is completely unknown or has no connection with you
The guy I talked to at the prom last night is a perfect stranger.