This question is really hard to answer mainly because Destiny is in such an odd position for a game.
Did you play the Beta? Did you enjoy it? If the answer is yes then pick up Destiny because the game has a wealth of content.
However if you never played the beta and still want to know if the game is worth your time well do you have a lot of time. The game has a huge grind similar to reaching max rank in Halo:Reach. If you do have time to spare then do you have friends to play with? The game is loads better with friends, playing alone will only get you so far.
I personally really like Destiny for the lore, gear, and character/class customization. The combat is very slow but still snappy and feels good. My biggest complaint is the 30 FPS.