Diablo 3 was a game I greatly enjoyed, but it wasn't without its flaws. The Auction House was a failed experiment, the loot system seemed tuned entirely to fuel said auctions, artificial gating of difficulty modes was an anachronistic concept, and the storyline was met with much derision. With the Reaper of Souls expansion, Blizzard has fixed many of the problems the original game had, while adding new content, a host of new features that improve quality of life for players, and a structured endgame for those who can't stop clicking.
First on the list of added features is the new Crusader class, a holy knight who wields enormous shields and flails. Crusaders are more of a tank archetype, with the ability to taunt monsters into attacking them, and a wealth of defensive abilities. While certainly enjoyable as any of the other classes, I've found they do particularly well in co-op, since they can keep enemies off of ranged classes that excel in damage. There's a bit of a question in the playerbase right now as to whether or not they actually fit the tanking role better than Monks, but that will probably sort itself out over time.
Reaper of Souls also adds an additional act to the core campaign. Act 5 takes place in the kingdom of Westmarch, and is primarily concerned with a fallen Angel named Malthael who has decided he would like to wipe out all of humanity (and demonkind along with it) to end the Eternal Conflict. It's still mostly overwrought nonsense, but the new zones are beautiful, the bosses challenging, and the world feels much more alive. And the music. My goodness, the music is just fantastic.
While earlier acts in the game contained random events sparingly, they're all over the place in Act 5, and many of them tie into the overall story. If you are thorough and speak to all of your crafters and followers, you'll be rewarded with events that cap off their particular storylines.
You also meet a new crafting NPC - Myriam the Mystic. Myriam is one of the keys to making your never-ending quest for loot a little easier. Get a sweet sword to drop, but one of its stats just isn't jiving with your character? Myriam will let you (attempt) to replace that stat with something more useful. You can only replace one stat per piece of gear, but you can keep trying to get the perfect stat roll for it until you're satisfied (or run out of crafting materials). She can also transmogify your gear to look like any other piece of normal gear. If you're lucky and start collecting legendary drops, you can pay a steeper fee and make your normal items look like any legendary piece you've encountered.
Once a single character on your account clears Act 5, all of your characters get access to the biggest feature in Reaper of Souls: Adventure Mode. In Adventure Mode, the entire game is open for you to explore or take on Bounties. Bounties are quests to clear small dungeons, kill special named minibosses, cleanse cursed chests, or take on the game's major bosses.
Adventure mode contains a significantly higher concentration of enemies, champion and elite packs. Once you complete a bounty, you'll receive a large amount of gold, experience, and a new type of currency called a Blood Shard. Blood Shards are exchanged with a new vendor in town for “mystery” items - which is similar to the old gambling system in Diablo 2 where you would purchase an item of indeterminate quality for a large amount of gold. Most of what you purchase will be of middling quality, but if you're gunning for a specific gear slot it's a good way to focus your efforts. Once you clear all of the bounties in an act, you'll receive a Horadric Cache that contains a number of crafting materials, items and even the odd piece of legendary gear.
During your adventures, you'll also receive Rift Key Fragments that grant you access to Nephalem Rifts, which are challenging, randomized dungeons filled to the brim with elite monsters. Rifts can have some surprising elements, such as encountering a room filled entirely with treasure goblins, floors of the adorable monsters from Whimsyshire, or even a fabled zone populated with bovine enemies. Killing monsters in a rift begins filling up a meter on the right side of the screen, and once you fill it up, a random boss shows up. Killing the boss earns you a good deal of loot, and a pretty sizeable stack of Blood Shards.
Adventure mode also allows for some more meaningful co-op than simply playing the campaign together. Players can split up to complete bounties alone, but all players in a game get credit and completion rewards, so things get done a lot faster. Since Nephalem Rifts require keys to open, it's more efficient to have as many players as possible in your game each time you open one so everyone maximizes their loot potential. Besides, with the new “bound to account” restriction, the only way other players can trade you for legendary gear is to be in the same game as you.
The Paragon system has received a complete overhaul. While Paragon levels are still accumulated after you've maxed your character level, rather than simply giving small core stat upgrades and a boost to magic find, you'll now put points into a series of four skill trees to boost whatever your character might need. Want extra attack speed? Need to boost your elemental resistance? Go right ahead. You can also reset your point allocation whenever you like, in case you need a boost. The points are now account-wide, so even a level 1 character can take advantage of your bonuses if you want.
Aiding in organizing co-op are new social features such as Clans and Communities. Clans are more structured, with the ability to set officers, messages of the day, and so on. Legendary loot that drops for any player in your clan is broadcast to everyone to see and salivate over. Communites are more basic, providing similar functionality for smaller groups of friends who might all be in different clans.
If you play Diablo 3 but haven't pulled the trigger on Reaper of Souls yet, it bears mentioning that the most recent patch gives you all of the gameplay and balance tweaks, such as the new loot and paragon systems, as well as clan and community support.
All in all, Reaper of Souls does an admirable job in fixing the many problems that Diablo 3 had with longevity. Much like Lord of Destruction before it, a Diablo expansion has redefined the core experience and erased many of the concerns that once existed. About the only feature that players are missing from the Diablo 2 days is a ladder system, and Blizzard's already announced one is coming soon. For now? I'll be Rifting with all of my friends and our new, shiny Co-Optimus clan. Come join us!