Product review (3 stars): Works well as advertised, but isn't actually any better than just handwashing
It seemed like a good idea. Like many New Yorkers, I have no laundry in the building, and the schlep up and down stairs and down a few blocks in the cold of winter was getting annoying. We tried delivery/pickup wash&fold, and while that's really quite convenient, too expensive to do on a regular basis.

So I tried the Wonderwash. It worked great, just as advertised. I was happy with it.

Then I tried just handwashing without the Wonderwash, putting clothes in a tub, filling with water/soap, moving it around energetically, and repeating a couple rinses.

As far as I could tell, both methods took the same amount of time and effort, and the clothes were the same quality afterwards. And I have tried both several times to keep comparing.

Some of the reasons handwashing was easier (allowing it to balance out its annoyances) included: Having to deal with the suction cups every time in the bathtub, having to deal with the pipe, the fact that the drain pipe broke within a couple uses, difficulty getting water into the tank quickly without some MacGyvering.... the fact that you can't fit as many clothes in there compared to a larger washtub so would have to do more loads....

So my conclusion is, if someone is offering you a Wonderwash for free or for less than the cost of a large plastic washtub (usually <$10) then go for the Wonderwash. If you actually have to buy it at $40, don't waste your time. It's bad return on investment when it does not save you a second of time or annoyance beyond what the $10 large plastic washtub would.

And it's less versatile than a large plastic washtub and may take up more space (due to not being able to store anything in it).

So, if you are interested in this thing and haven't tried handwashing before (or at least not recently) try handwashing first, you might be surprised how much easier it is than you thought, especially after practicing a few times to get your speed up. You can always try the Wonderwash later if you're unsatisfied.

That was the case with me, I overestimated the annoyance involved in handwashing and assumed I needed a cool invention to save the day. But I didn't.