Its the King of the roost. Play it solo all the way through, play it offline or online, explore and play any area on its own for kicks, or do randomized bounty runs, or campaign missions, or special Nephalem rifts. Play with your friends no matter what the level disparities may be, and every time you play, there are dynamic elements to keep you on your toes, not to mention 9 difficulties. You have a shared gold account and vendors and materials and a shared chest, and leveling doesn't end at 70 as you continue to gain paragon levels that apply smaller, hand-picked increases to each character you run. Legendary equipment is also more than just bigger numbers - most come with unique gameplay effects.
This game is the real deal. 1080p, 60fps and polished to a gleaming shine too.