So Reaper of Souls is really fun and BlizzCon even more so! So here are my impressions of everything Diablo-related that they showed at BlizzCon.
The Crusader class feels soooo good. He's the perfect blend between close-combat melee and ranged. This is how I played with the skills that were available on the show floor. I'd run up to a group of monsters and start generating Wrath with the Punish skill, then smashed them with Fist of Heavens, which does a huge amount of damage. Then I'd use the Steed to charge to the next group and cast a Fist of Heavens on the upcoming group. If there was an elite pack, I'd first cast the Falling Sword, doing huge amounts of damage. Then I'd set up a healing area with Consecration, activate Laws of Valor, and start attacking. If there was any issue, I'd use the Steed to escape.
Wrath seems to work exactly like Spirit, only generating when you attack and spent via skills. However, there were a couple more ways to generate skills, such as some sort of blocking skill that I can't recall too much.
A passive I really enjoyed was the one that allowed holding a shield and a two-handed item. I managed to get a Legendary two-handed item and used that passive. The speed decrease wasn't super noticeable because of the charging Steed. Already there there seems to be a couple of ways to play the Crusader. You can be a tank and take the damage for your team. You can deal tons of damage up close. You can run around the sidelines and deal ranged damage from there.
Westmarch is looking amazing. If you wanted dark Diablo 3 (or if you didn't want it), you're about to get it. You get thrust into killing the reapers right away. You actually have to fight your way to the town the first time you enter. The side dungeons are looking more involved with the characters. The first side dungeon I entered, I had run around inside and protect three groups of peasants from attacking reapers. Completing that gave me a lore book. The other one I remember was me attacking more reapers with archers helping me out. Once that area was completely cleared, I moved into the next section.
The way that some minions are spawned is really cool. There's a section where you're just walking over an alley full of dead bodies, and the top half of zombies start popping out of literally nowhere and attacking you. Bats started descending from trees while I was fighting an elite pack and almost killed me.
The music. Holy shit, it's great. The one thing that truly stood out with the music is that it progressed as you progressed through the area. There was a bell sounding the background when you first enter the area, but it's barely audible. As you get closer and closer to the end of the stage, the bell gets louder and louder until it's dominating the music. And this is a bell that sounds like it's announcing the end of days.
Adventure mode is what tons of players have been asking for. You can go to any waypoint you want, from anywhere. They haven't decided on when you can unlock it, but I think they were leaning towards having it unlock after one story mode play, which makes sense. The two additional systems are Nephalem Rifts and Bounties.
Bounties are the random side-quests that you get from every act. They're varied, from killing certain purple mobs, to killing bosses, to clearing areas. Some bounties were quick, while other took time. Completing all five would probably take about 30 minutes. You get gold, experience, nephalem rift tokens, and I believe a chance for either crafting mats or a legendary item. You can view which items will drop from each act, along with what stats they can roll. So you can decide to try and get a specific item and do bounties from one specific area.
Nephalem Rifts are so much fun!!!! Completely randomized areas and monsters and environmental effects (which I'll discuss later). As soon as you enter an area, you see a bar on the quest area. It starts filling up as you kill monsters. Once you get it to 100%, a boss gets summoned in your immediate area, no matter how many enemies are there. The areas are grouped in sets of two, so level 1 and 2 are from the same act, level 3 and 4 are from another act, until 10. Getting to 100% is also varied. One playthrough took me only two levels to get to 100%. With the other playthrough, I was only around 70% on level 4. Once you kill the boss in the rift, you can continue through it, but there's no more chance to get another boss. The density is varied and the monsters are also amazing. Some of the elite packs were at least twice as large as their normal models. There were also packs of keywardens that were really tough.
What helps you out immensely is the new shrines that are only in the Rifts. From one of the developers: "We basically tried to break the game as much as we could." These shrines are sooo good and last for 30 seconds. One removes all cooldowns and resource costs, which caused me to spam Fist of Heavens, then charge to the next group, fist of heavens, then charge again. Invulnerability makes you shielded. There's one that boosts your damage by 400%. One that gives max movement speed, one that basically electrocutes everything to death. All these shrines kept me constantly moving, even though normally I might pause or take longer to kill enemies.
Toughness is replacing armor as the basic stat that's displayed. No more need to go to D3up to see your EHP. Life is now replaced with Healing, which is a mix of all the life affixes.
Four Passives are now available at level 70. Not sure how I feel about this, but I haven't been able to test it.
Items now display stats as either Primary or Secondary. I'm not exactly clear about the distinction but main stat and important stuff that directly affect health and toughness and DPS go there. Secondary attributes are other stuff, like reduced cooldowns and whatnot. I'll be asking about this tomorrow.
Paragon 2.0. This wasn't something available to play test, but you could see the categories and the stats to put points in. It's definitely something that will change with your gear. You might find a piece that has Magic Find, so you can drop your points in Magic Find and dump them into movement speed or more resource.
Environment effects were actually much cooler than I expected. Previous areas I explored in the Rifts appeared darker or sunnier than their originals, which really gave the areas a different appeal.
New monster affixes are pretty interesting. There's a poison enchanted, which roll out poison ground in a plus formation and stay around for a long time. There's a new frozen orb affix that spawns orbs that continuously chill and do damage to you. Jailer appears to have been updated as well: a small circle is created around you. If you can't get out within a second, you're jailed.
Also, I geeked out at the Lore Q&A panel, so if you want to hear my lore questions, go watch the VOD of that. I asked a ton of questions.
There's probably a lot I forgot, but I was super busy and now I'm super tired. Ask away and I'll either answer, or try to get an answer from a developer or CM tomorrow!
EDIT: I got to talk with a ton of the developers and designers and writers and artists. Most of them browse reddit. I can't remember who (I'm so sorry), but one of them said they had fun reading reactions to datamines, because they knew that some of the items that people were discussing weren't actually going forward, but were really interested in people's excited reactions for items that actually were planned for release.