Pro MMO experience
An MMO experience in a FPS game; Bungie has done quite well with making attaining gear and weapons enjoyable through single and multiplayer content. Taken King made the grind much less of a chore and more enjoyable as well, and made the whole leveling process better with refinements to all aspects of the game.
Pro Created by Bungie, a well known studio for making quality games
Created by the same company that created Halo, this spiritual successor has the familiar feel with some refined game play and the polish and quality you'd expect. The DLC coming out with Taken King has also been good, and expand on the game quite nicely.
Con Imbalanced multiplayer
While stats from gear is equalized during multiplayer, perks from legendary weapons and armor give a real advantage to players who have put in more time. Not a problem that makes it unplayable, but newer players might get frustrated when skill is not the only factor.