The gameplay is simple yet fun, and the art is very nice as well! I also like the music that plays during the gameplay--keeps me focused to not miss a package!
Though, I do have a few critiques. The first is that sometimes, the packages hide themselves behind the UI, making it harder to make out where they are (and what belt they need to go on). Maybe you could make the UI semi-transparent to help with this? The second is that, after putting a package on a conveyor belt, you can keep clicking on it to rack up points. I'm assuming this is unintentional.
Regardless of those critiques, I really enjoyed the game! Good work! :-D