This game is really strange. It has great qualities, but in the same time can be a nuisance. First of all, when one starts playing you really don't know what to do, what quests one should do. You have no clues whatsoever. So, one has to use walkthroughs in order to know what to do. But after having figured out, the game is fantastic. The gameplay is fantastic; a real shooter with SF taste. You have weapons and gear that can be upgraded. You level up and you can gain new gear. There are many quests, but the story could be considered good enough, if it weren't so confusing.
It's not an open-world game; you simply drop on the same spot over and over again. And that is infuriating.
The Taken King is much better. It has a better story and greater bosses. It's not a difficult game at all. It reminds me of Borderlands, but the loot is scarce.