I enjoyed that, nicely implemented and great presentation :)
As others have said, it's not easy and it gets the bloody pumping. I think having more time on the timer would've been nice, also starting off much slower then ramping up the speed gradually would've been good too.
Sometimes the boxes and zip bags got stuck on the exit conveyer belts, perhaps some invisible collision might have helped to funnel them in. Sometimes they are too far away to sort them out with the controllers.
All in all, nice game - I had fun playing it.