Popularity doesn't mean a thing. I liked it, NOT because of popularity (LEGO games aren't that popular) but because I'm a die-hard Harry Potter fan. (Cue the trolls). It's a decent game overall. Controlls are good and cutscenes are definetly hillarious. I'm not saying I'm definetly gonna buy the sequel, but I might rent it.
The moral of the story is: rent it based on how you enjoyed the first game and not for popularity.