Yes, I think this game is certainly worth the money. The online mode is almost perfect (Ten times better than Brawl's). There are a lot of characters, a battle mode, time trials, and many retro courses have returned. The one thing I criticize the most is the battle mode. In battle mode, you have to be on a team. Honestly, I like free-for-all better.
But other than that, it's a good game.