Got a Joe Blow II for a similar price.
It's got about 12mm tread and they cost about £150 a corner so more likely get it repaired at some point. (y)
It's more to top it up when camping, they lose pressure after a few days (apparently because the material flexes/expands rather than any leak). We use 12V car inflator but that would mean dragging the airbed out of the tent to top it up.
I've had one in the past and just found it noisy, slow, tacky and not very effective. Maybe they've moved on. :)
By law they garage has to let you use the their inflator if you have no money on you and your tyres are not inflated to legal standards. "A lot", never "Alot".