I’m so-so

Although not wrong, ‘so-so’ is seldom used in English.
Instead, people use words such as ‘OK‘, ‘alright‘, and ‘not bad‘.

WrongRight
“How are you?”
“I’m so-so.”
“How are you?”
“I’m Ok.”
I’m a so-so swimmer.I’m an average swimmer.
The party was so-so.The party wasn’t bad.