I agree with the other comments. It gets much too hard, much too fast. I spend half my time trying to organize my junk so that I can easily keep up with the orders, but while stacking boxes, I get orders upon orders for nukes and tires, which I get maybe once every other lever pull at best. This leaves me stumbling and stuck on iron bars and barrels. Meanwhile, the customers are all getting angry, and by the time I fulfill one complicated order, the other complicated orders are all filling the "angry customers" meter.
I would REALLY like the option to control when the shop is open, so that I can give myself a minute or two to give myself a walking path between waves of customers.
I saw you mentioned long ago the idea of adding a sandbox mode, which I think would be highly appreciated by many people.
EDIT: It'd be much less stressful if the customers had individual timers, which resulted in the customer walking away instead of ending your game. That may be easier to implement than a whole new mode?