The graphics of the game look good, but there are several different visual qualities noticeable throughout the game. For one, there are many clips taken directly from the movie. These are highly-detailed and almost look like actual LEGO pieces. The next level down is cutscenes made specifically for this game in order to fill in some of the gaps between the game's more detailed story and that of the movie. While these don't look as good as the feature film's clips, they still look pretty good, but there is a distinct difference between both the higher-quality video and the slightly lower-quality gameplay graphics.
That's not to say that the in-game graphics aren't good. On the contrary, they really do a solid job of conveying a massive LEGO world, it just doesn't come off quite as well as the cutscenes. Unfortunately, I did notice several instances where the game seemed to chug when there was too much happening on-screen. This was rare, but it happened, and typically only when there were a lot of studs lying around with several enemies running about and even some extra effects in the background like a building on fire.
Ninjago's sound department definitely gets the job done. It's not clear if the actors from the movie were able to reprise their roles for the extra dialogue in the game, but if not, then the voice actors that are standing in for their big-screen counterparts sound right, which is really important given how frequently the game shifts between actual clips from the movie and game-specific clips. A sudden change in voices between the two segments would be jarringly apparent, even to my untrained ears.
The game's music is also very fitting. The background tunes have the appropriate feel that seems to resonate with the odd East-Meets-West world that is Ninjago Island, while environmental sound effects set the mood appropriately. Everything from city sounds to jungle noises do their part to make each level feel unique and right.