Reaper of Souls is meant to fix Diablo III. Blizzard may not put it exactly that way, but it doesn't take a lot reading between the lines to realise that they're not entirely happy with how Diablo III came to play out in a number of areas. And that's putting it mildly.
The biggest and most important change is two-fold. The much criticised auction house has been removed, while Blizzard introduce a new system for loot drops. They called it "Loot 2.0" - and the idea is that the loot you find should be more applicable and useful to the player.
Judging by our time in the closed beta, Blizzard has accomplished this. Naturally stuff still drops that is useless, but you will also frequently find appropriate gear for your character. And the flow of loot is steady. The rest of the items you can sell or scrap, and use the materials to craft new equipment. The crafting has also been overhauled, there are now far fewer materials, and you use the same materials regardless of whether you're level 10 or level 70.
Reaper of Souls isn't only designed to correct some of the flaws of the original. Blizzard has naturally also fleshed out the content side with three major additions.
First of all there is a fifth act. It adds new locations, a wealth of new monsters, and a new level cap at 70. Act 5 plays out in and around the large town of Westmarch, the wetlands surrounding the town, the catacombs underneath it, and Pandemonium - an ancient battleground in another dimension where heaven and hell have fought since the dawn of time.
Unlike the original game, where game dungeons were randomly generated but the overworld never changed, all environments (bar a few exceptions) are randomly generated each time you start Act 5.
Simply put it's a new experience each time you play, and it should also be noted that the game world is more frequently populated with little dungeons and events. No longer is there any point to learning the geography by heart and checking a few hot spots. The art style is also gorgeous, from the dark and gothic look of Westmarch itself to Pandemonium's supernaturally flavoured architecture and seemingly endless expanses.
Another major addition is the new character class, the Crusader. A heavy set lad (or lady) with shield and armour that makes his or her way through the horde of enemies at close or medium distance. It's too soon to pass any judgement on game balance as Reaper of Souls is still being worked on, but the Crusader quickly became my favourite class for several reasons. First of all the Crusader kicks ass and smashes through the enemies, and the abilities it wields are useful, aggressive and clever, to such a degree that my Monk and Demon Hunter come across as a bit boring in comparison.
My build consists of a standard attack that adds a bonus to your chance of blocking each time you hit someone. It's been enhanced with a rune that makes your shield explode in an Area of Effect attack each time you block. On the right mouse button I have an attack that disposes of most low level enemies with one hit. Another ability sends a line of four ghostly bowmen towards the enemy - cutting down and shooting down anything in their path. The Crusader is given extra mobility by summoning a horse (made of divine light, or something to that effect) capable of riding through enemies, and an ability called Sword of Heavens - described by Blizzard as something of an artillery strike where you are the projectile. A perfect mix of usefulness, massive damage and cooldown - and it's always very satisfying to trigger it.
The Crusader is simply a wonderful class. At this point it appears almost overpowered, but I'm not sure if that's just how I perceive it.
The third addition is Adventure Mode. Blizzard's new attempt to add variation and an improved end game. In Adventure Mode there is no story, no quests or cutscenes. All the waypoints are unlocked, so you can travel back and forth between all five acts and their dungeons. Along the way you get so called Bounties - short mini objectives tied to a single waypoint. Typically they task you with killing 50 monsters and a specific elite, or complete a certain event. For your efforts you're rewarded with gold and Blood Shards - a new currency you can use to gamble on new equipment.
A bounty is quickly taken care of - only seldom will they clock in at over ten minutes. Each act has five bounties, and if you collect them all, you're in for extra rewards - more gold, shards, and a Horadric Cache - a pouch that spawns loot when opened.
At times you will also get your hands on a so called Rift Stone - that you can bring back to town and use to open up a Nephalem Rift. These rifts are temporary dungeons featuring one to eight levels - where existing assets and environments are combined in new ways and lit differently, and where enemies from all parts of the game come together. The difficulty level is naturally a bit higher than it is out in the world, with plenty of elites and uniques. As you'd expect you're in for even better loot than you'd find elsewhere. When you have slayed enough monsters (the target isn't specified, you simply go by a percentage) a boss spawns, that once again, offers the opportunity to score even more amazing loot.
It's a brilliant mix of a quick fix and more sustained challenges that gives Diablo III much needed variation in addition to the old Valor stacks and Inferno runs. Best of all is that you can play Adventure Mode regardless of your level - the game automatically tunes the content to cater to your character. Theoretically you will be able to level all the way from level 1 to 70 without ever touching the story.
The previously mentioned Nephalem Valor and Inferno difficulty levels have been done away with. Reaper of Souls introduces a difficulty system much like the one you might know from the console version of Diablo III. This means that progression is more tuned to a single play-through than four, and you can adjust the difficulty setting along the way. The hardest one is unlocked once you've reached a set level, but you don't have to tread far until you'll want to raise it from Normal to Hard.
Judging by the closed beta, that contains pretty much the full expansion with the exception of the final boss fight, Blizzard really hits the nail on its head this time. Diablo III is given a major vitamin boost across the board. It appears to be a must for all Diablo III owners, regardless of whether the original game left you satisfied or not.