First off, I need to make this perfectly clear: I thoroughly enjoy Diablo 3 and feel it fully warranted the money I spent on it. Not only have I been able to play with my friends online, I've made new friends as a direct result of this game, which is pretty amazing. However, there are two ways I look at Diablo 3: one way is just as a game, the other way is as the sequel to Diablo 2. Needless to say, when you truly enjoy a game and a sequel is announced, there is always going to be a combination of trepidation and excitement. Here's what wowed me with D3, and what disappointed me.
Cinematics: While a number of the cinemas are told through medieval-like etchings, the ones that feature full CG are absolutely stunning. The voice acting is also decently done as well, and the package comes off as a huge improvement to Diablo 2.
Accessibility: Diablo 3 needs to be recognized for just how easy it is to pick up and start playing, even for someone who has never heard of it. Normal mode makes things easy, slowly giving you more and more freedom. By the time you complete Normal difficulty, you know there are many more challenges down the pike and are equipped to handle them.
Battle System / Action Bar: The new implementation of the action bar is fantastic and gives you access to 6 different skills at a time. Enabling Elective Mode allows you to further tailor your character's customizability to how you want to play. As for the actual combat, it's fast, furious, and fun and certainly requires some strategy. While certainly fun solo, bringing up to 3 of your friends into the cursed world of Diablo is even more so. While playing multiplayer, you really get to know your character's role and strong points in a way you simply can't going solo.
Interface: The interface of Diablo 3 is about as good as I can imagine. Managing your inventory, skills, friends, and chats are all intuitive, quick, and responsive. This only adds to the overall quality of the meat of the gameplay listed above.
Scale: I know that probably sounds strange, but what I mean is the sheer scale of the number of enemies onscreen. It actually makes you feel like this is a huge war, especially in Act 3 where you have hordes upon hordes of enemies who want nothing more than to wipe you out.
Deckard Cain's Dance Moves: Last I knew, Deckard Cain has a little bit of a glitch now where he appears to be dancing in Act 1. Needless to say, it's utterly hilarious and hopefully it has not been fixed. You keep getting your groove on, Cain!
Bosses: With the exception of Belial, who was a fantastic multi-tiered boss fight, I thought the denizens of the abyss were a bit unimaginative. Many of the bosses have the same basic abilities that any elite/champ would have (like Izual with his frozen ability, Magda with her shielding ability, and the Spider Queen with her plagued ability) and the big boss fights leave something to be desired. I honestly expected a lot more from Diablo, and they could have pulled out the stops more with him.
Environments: Granted, the environments are well rendered, no arguments at all there. However, many of them look all too similar to each other and for the most part they're also quite generic. I mean you have your forest, your swamp, your desert, and your snowbound plains. Most of the dungeons you head into wind up being similar looking caves or rustic buildings of some kind. Truth be told, pretty much all of the dungeon ideas have been done before and done better.
Skill system: This will be a soft spot for many, but I enjoyed Diablo 2's skill system far better than Diablo 3's. While I fully understand they were going for accessibility, I believe they could have done so better. The same aura of experimentation could have been achieved with leaving Diablo 2's skill system intact along with the ability to reset skill and/or stat points either by paying EXP or Gold.
Weapons and Gems: Beyond Act 1 Normal, Normal/Superior items are pretty much useless. Not only that, they're worth such a small amount of cash that they're meaningless to pick up. Why couldn't they have at least some role in the game? One main idea would be crafting to that end. Also, the number of gems has dropped from Diablo 2 and it would have been nice to have seen more of them with a wider variety of effects. Finally, the ability to remove gems and have them stay intact may not necessarily be the best move, as it will undermine the value of high level gems on the auction house.
While I agree with most if not all of the above, especially the dancing Deckard Cain, there are some others that are disappointments for myself as well:
Auction House: The Auction House is essential in this game. Without it, you will not be equipped for Inferno. End of story. You need to farm gold and buy better equipment to make it through Inferno alive (unless you find a glitch of course or get extremely lucky finding the right items by farming). Also, if you are looking for a particular legendary or set piece with certain stats you cannot filter on stats or the specifics you want. You have to look through each one until you find the one you want. With sets and legendary items having completely different stats for the SAME ITEM, not being able to search for say a Sage set piece with dexterity instead of strength is a tremendous pain. Hopefully this is adjusted in a future patch.
Trading: Speaking of the Auction House, it has reduced the need for trading in a good and a bad way. The good would be that you no longer have to hunt around for items anymore. You just go to the Auction House, filter on the items you want, with the stats you want, for the price you want, and buy away. You don't have to find someone with the item you want, with the stats you want, and then find something they need in return to trade (only to leave disappointed). It makes it easier but it removes the whole bargaining process which was something i truly appreciated in Diablo 2.