Is investing in officetels for monthly rent a good idea?

I own an officetel in Bupyeong, Incheon; it's a 1.5-room unit and is about 8 years old.
It's a 5-minute walk from the station, but the downside is that the window has no view..
Since I am a multi-homeowner, it hasn't sold even though I put it on the market, so I am currently receiving monthly rent.
I get 5 million KRW in deposit and 700,000 KRW per month.
Is this considered decent, compared to a savings account..