It degrades in a few weeks in a heated industrial composter, and it doesn’t meaningfully degrade in a sensible amount of time in natural conditions. It has the potential to be less bad than other plastics, but anything that biodegrades in a similar way to food is going to go off at a similar rate to any food it’s containing, which is obviously bad for packaging.
If your municipal waste is handled responsibly, then landfill at least seals the carbon away, whereas burning the plastic or some of the more controversial varieties of recycling put an equivalent amount into the atmosphere. It’s a big if, as there are loads of ways a mismanaged landfill can contaminate the environment, but it can be one of the least bad things that happen to oil once it’s been dug up.
I don’t think this nuance is what the other poster was driving at, though.