Just flown a couple of flights with UL. Quite a disaster airline.
It took them 30+ minutes to check me in due to poor understanding of how their own systems work.
On board people move all around C cabin and change the seats even before doors are closed.
Constant flow of pax from Y into C cabin to talk to their friends and use C lavs.
I only wanted to sleep but no, has been waken up and asked if I wanted to eat
A friend on another UL flight had very similar experience.
So may be OK if you get it very cheap and keep your expectations very low. But don't expect proper C experience - you get what you paid for and even less.
Regards,
El Puerco Volante.