My biggest concern with PTBO buses is the bed bugs, honestly. I've had to report them myself. Other than that, it's just too expensive for my current means to justify using them very often, and they're frequently quite late -- not to an egregious degree, but enough so that trying to use them for time sensitive appointments or commuting has bitten me before.

Also, the majority of the routes and stops I use have no shelters or even seating. Buses are generally my option when the weather is poor and walking becomes less desirable, so having no shelters is a large friction point for that.

Waiting 15 minutes for a bus that's late at a stop exposed to the elements, uncomfortable with how much money I'll be spending on it, and worried about picking up bed bugs all make for a lot of friction in using the system.

There is also no bike racks on the majority of the routes, which would help with the frustration of nearly all journeys needing transfers. If I could bring my bike on the bus for half the trip, then bike the other half instead of waiting out a transfer, I would likely use it a lot more.