They're a massive multinational company and own many units in the buildings, so be mindful it might not specifically be the unit in the pictures. They'll be comparable layouts and furnishings though.
They're a bit of the antithesis of what you'd expect on Airbnb but the flats are nice and well maintained and offer contactless check-in which is pretty smooth.
We had a lot of hiccups in our trip but because we booked Sonder we had flexibility to add days to the front and back of our visit which was nice.
COVID conscious travelers may find issue with the lack of guidelines being followed in the units, but for those hungry for an Airbnb experience of the pre-pandemic days this might be more than welcome (i.e. no plastic bed sheets!).
You're unlikely to ever correspond with the same person at Sonder twice, and this was a huge downside for us as it delays the resolution of problems as you might have to talk to 5 different people to resolve something that should have only taken 10 minutes.
I'm on the fence on whether or not I'd recommend Sonder to a friend. They've got prime locations and nice suites, but I still came out of it feeling I'd made the wrong choice.