The washing quality with brushes has always been good and with the subscription the service has pretty good value for money for someone who moves a lot and needs their van clean after longer trips. Special mention for the vacuum cleaner option.
The downsides are random mystery options in my washes. I have the basic wash with brushes, but I've gotten what looked like the premium version and then several brushless washes. The failures have also included the system stopping mid-cycle, forcing me to call their service number.
I'm also not sure if the status of the car wash shown on their site is accurate, I've left to wash my car several times with the status showing green, only to see the place completely dark with traffic cones in the way, or a service person working inside.
I haven't had much issues with having to wait, usually I'm the only one after 23 hours, but in general it could use for example a machine-vision based estimate of the queue length.