Well, even a mediocre Lego game is still above average overall. This one's short. It's got some bugs, but most Lego games do. Honestly? This game is OK. It follows the movie fairly well, but there are points of divergence. And more than just "makes for a better video game". There are parts that honestly felt like it was an earlier draft of the movie. Which wouldn't surprise me. The game was released the same day the movie hit theaters. That strikes me as a bad idea. You haven't given the movie time to build interest in the game, and the parallel development means that if a change is made for the movie, the game lags behind. This was most noticeable with the cut scenes. They were taken from the movie, but the music is wrong - when it exists at all. Music is added fairly late in the film, and it's entirely possible that the scenes were sent to the game before the music was complete. The music that does exist smacks of "temp tracks". It's just not good, doesn't fit. One scene in particular, taken from the movie, references a specific song.. that's not in the game. Which makes that cut-scene particularly awkward.
It has an interesting mechanic in the swapping of pants. You can unlock pants that give you an effect in game. There's only a couple effects that actually make any real difference. And it's more "good idea, bad execution" than anything else. The fact that some of the pants are only available via codes found with the Lego sets for the movie troubles me. Not that the codes are hard to find. I'm sure they were online the day the sets were released, if not sooner. I don't really mind it for something like the alternate character model that the DVD/Blu-Ray comes with a code for, since that's purely cosmetic (though it does give access to a character and thus its abilities sooner). The pants, on the other hand, do have an effect on the game. Again, only one has any major impact, and there's a similar - but not exact - pair in the game you can unlock. Maybe I'm just being a curmudgeon here, I have nothing really against cross promotion in general. As long as it's cosmetic.
Overall? Well, the game was on sale, so it's not like I paid anywhere near full price for it. And I certainly got my 'money's worth' out of it. But, on sale is really the only time I would recommend this particular game. Especially given the quality of others in the series, such as Lego Star Wars III and Lego Marvel Superheroes. Still, if you are looking for more Lego games to feed your addiction, this one can fill the gap nicely.