I can't even count the number of times where I've had Uber drivers tell me they have no clue of where they're driving (i.e. I have a better understanding of the city than them) and they used to be UPS drivers before turning to driving for Uber.
If you are however disabled, have pets or a baby trolley you’ll likely have quite a bit of a problem with Uber et al. Black cabs are big and afaik all of them can accommodate wheelchairs.
Heck, one recalled Uber started off in the completely wrong direction, despite my protestations, getting caught in a local one-way system that took a good 20 minutes to get out of. I was not a happy bunny.
It's true, a lot of the older black cabs were loud and didn't have great suspension. I'm starting to see a few of these (http://www.theelectrictaxi.co.uk/) on the road now, which will at least be much quieter - not sure how the ride is but I'd hope it's better too.
And it's probably just me but I find the standard Toyota Prius more comfortable than the black cabs (esp due to engine noise and vibration). But obviously for quick trips within the cities they're still much faster than an Uber.