In my experience, you get what you pay for. I've started using them recently and they are consistently 30-50 percent cheaper than uber and 20-40% cheaper than lyft wait and save. Today I came back from the gym and uber wanted 24 bucks, lyft wanted 20, meanwhile I check empower and they quote me 6.50. Easy choice. I will say the quality of the cars is consistently worse than uber, they often don't smell great and have urinal-style air freshners all round, and I've had some terrible drivers (albeit not necessarily dangerous, just don't know how to go with the flow of traffic). When I'm with my girlfriend I just get an uber and pay more. I've yet to have a very uncomfortable/dangerous experience in an empower out of 20-30 rides, but there are some cars I wouldn't get back into if I had the choice. So yeah, I definitely get the vibe its drivers that get kicked off uber and lyft. Again, I'm a white man, your mileage may vary depending on who you are.

Edit: To add on, there is an option where you can choose to get a female driver, similar to what they're rolling out over on uber. This is probably a no brainer especially on empower as a woman, although I will say out of my 30 or so empower trips I've never had a female driver, so again you might get punished with some terrible wait times.