Not very good
In the later levels when the sets become more more complex, having to control the entire set in one direction all at the same speed is horrible. It completely ruined what would have otherwise been a fun game. Being able to control the direction and speed of each element individually would have made this SO much better.
Level 16 was absolute garbage for two reasons.
1) It was a matter of complete luck if you could get the box to "bounce" off of the left wall at the proper angle to get it to land on the lower conveyor. It had nothing to do with the level design itself, simply the fact that you're throwing square boxes. If it had been a round object, it would have been a non-issue, since it would be much more predictable in how it would bounce back.
2) Why exactly are we throwing boxes at walls with the hope of getting it to bounce off and land on another conveyor belt? "Your role is to transport boxes into bins using conveyor belts." Transport does not equate to "bounce this off a wall and hope it lands where you want it to. "This game is inspired my experience in a factory" I certainly hope this wasn't what you did in the factory.
Having no apparent way to reset the level before the timer ran out was terrible as well. Having to sit through 20-something seconds while I wait for the game to decide what I had already known at the start is just bad.
But the worst part was that there was literally no learning curve. You started players off with nice easy levels - relaxing, really - where the challenge was minimal, and then you threw them into sets like 16 and beyond where it came down to more luck than skill, and overall frustrating design. That was just disappointing.
I give you three stars for the earlier levels, since they were nice. Moderate challenge.