The never-ending box
It's a puzzle game, a classic, the definition of a puzzle game with all its typical features. It has nothing more, you will pray for your passwords and pray to finish some levels, you will fall into desperation and maybe you'll see some guide, but that's the spirit of the puzzle-games.
There's an incredible feeling when you end all the levels, because you know that there are really few people who have done it.
It's really really frustrating. When you start it and see the game you think that everything will end in level 100. No way. Then, maybe you think that you'll be free in level 150, but that's not the end. It has over 250 levels and it gets boring when you pass level 150. It's the same all the time. There are some maps which looks like the previous but they're not repeated, it's something like a Deja-vu.
The Bottom Line
If you want to dream with boxes for many days (maybe months) and want an infinite game, take it. If you have no patience, stay away from it.