This game has unending playability depending on your entertainment requirements; you can try any number of different characters, each with their own style of combat, fight tactics, and roster of attacks.
Street Fighter IV comes with a single player mode, multiplayer mode, energetic training mode, interesting and engaging bunch of challenge modes, a trial mode that introduces you to the beginning and more advanced attacks for the characters, and on line play that played great and was a very positive experience. All the modes were fun to watch or play, very engaging for the senses and a breeze to learn, especially if you've played a game in the franchise before.
Array of unlockable items and characters really is a fun element that all games should implement when possible, at least until they think of something better. You can collect things you can use on line, new colors and even verbal taunts for the characters, which gives you even more reason to play.