It's an old formula that seems to work for the LEGO games, but it's getting a bit boring.
There's a good assortment of characters, and each one has it's own special ability. There are a lot of side quests that will keep you busy for a few hours. Collecting missing items for people who are to lazy to do it them self. Finding Meathril to cast new items for your characters etc.
There's also all the normal stuff you would expect from a Lego game. Hidden collectibles through the stages which you can only reach with specific characters which you unlock later. Stud collection. Building sets.
The Bad: I really did not like the fact that they used the voices from the movie. It kind of took away that charm which was the LEGO games. It's not as funny as the previous games either. They obviously found a game that works for them, but they didn't add anything new to it. It's the same recipe as any other LEGO game and that can become a bit annoying. Smash stuff...get studs...buy stuff. We've been there and done that.
The graphics didn't work for me either. It was a bit pixelated, and things seem to render as you walk through the world. So it's not particularly sleek like previous games.
It was okay, but I think there are better LEGO games out there. If you are a major LOTR fan, you'll like it.