It is beyond my knowledge what kept me going, but it did.
The Good:
Instant 2 Player Co-op. Huge Replay value. Character Customization. Score modifiers (score X2, score X6, etc.) And Many cool characters.
The Bad: Unbeatable odds and frustrating moments. For example, in a level taking place on the death star, you must build a door to stop stormtroopers from attacking, they come in groups of 4 every 4 seconds. When they shoot you all of your progress is erased and you have to build the door all over while trying not to get shot. Or when an AT-ST is embeding you into the ground while shooting you and you try to kill it but you cant. Or when a Jawa disables your droid while you were trying to open a door.
Gameplay:
The gameplay can get a little repetative at times, but, with so many characters, hidden areas, and unlockables, you will play each level at least 5 times before you fully complete the game. What keeps me going is the character customization feature. You can creat endless cominations of lego people.
Rewards:
What you get in return for collecting all the minikits, powerbricks, obtaining true jedi, and unlocking everything is sort of disapointing. You get a stud fountain that endlessly spits out studs. By that point in the game, I don't need money for anything anymore. So it is rather pointless. but, it takes repetitive play to tire you of the games 18 levels.
In Summary:
In conclusion, it is a pretty good game with great sound, graphics, and replay value. It offers more features with every accomplished task. And the Character creater alows for a few hours of extra fun and experimenting.