Can someone summarise why this game is popular? I looked at a Youtube video of someone playing it, the beta I assume. The guy was playing a barbarian. He was strolling around killing everything and trashing the landscape too, with two swords. He was just mouse clicking and everything around died. Leveling up very quickly. No skill or strategy appeared to be required, just clicking repeatedly and everything you see on the screen dies. What else is this game about or is that it? This is a genuine question, as I go ripped off buying Battlefield 3 a few months back, only to find it was just point and shoot and no skill or tactics required. I am curious to know why it is currently #1 on amazon for a PC game.
For me personally it's a lootfest, I guess a small challenge is grinding your way through the game to Inferno Difficulty Level where you can then get your hands on the most epic drops, but then the bigger challenge is farming for those drops using appropriate equipment (some items increase your chances of finding Magical Items, for example).
For others it'll be the PvP aspect (PvP isn't included at release but will be added later according to Blizzard) where equipping the right skills and loot will be paramount.
Finally, if they have a secret cow level like Diablo II did, then you'll probably need a fair amount of skill or time-invested in the game to beat it.
Firstly, you can't get a very good impression of the actual gameplay from the beta. The beta only included the very first part of the game, which Blizzard have routinely said is just an introduction/tutorial and people shouldn't base their entire impression of the game from it. They actually admitted afterwards that it was very directed and was meant to be easy.
Diablo 3 is popular because pretty much everyone who played Diablo and Diablo 2 has been eagerly awaiting it. What makes the franchise popular is the same as what makes games like World of Warcraft popular: loot, character progression, and, most of all, killing things. People get a lot of satisfaction out of destroying lots and lots of enemies all at once. There's also the story... There's a lot of lore behind Diablo, though most people don't care about it except for the boss fights (and, of course, Diablo himself). Look up the cinematic videos of Diablo 2 and more recently the ones currently out for Diablo 3 and you'll see what I mean.
As for your main question if you need a brain to play Diablo 3... You will do, yes. Mindlessly button mashing is only going to get you so far. There are a lot of things you need to think about: builds (your selection of skills), what equipment will be best for you, and how you should approach certain types of enemies and bosses without dying. There is surprisingly a lot of thought required in Diablo, particularly once you get past the normal difficulty; that is where a lot of the action happens, and in the case of Diablo 3, it is likely that Inferno will be the main aim for people to dominate in. It's meant to be extremely difficult and WILL require a lot of thought. This is even more important when you're playing with other people, because everything gets harder, requiring cooperation and planning.
Your uncertainty towards Diablo 3 makes me think it may not be the type of game you like playing, at least in the past. If you need to ask this this, you obviously haven't played the previous games, nor other games like Torchlight, Sacred, Nox, etc. (there are so many others I can't recall right now). If you feel you were ripped off from buying Battlefield 3 because it didn't require skill of tactics, perhaps you should wait until a while after Diablo 3 is released. Get opinions of other people, try out similar games, or just hold out for the demo (starter) version that I believe Blizzard are intending to provide; when or if they will, though, I have no idea.
No skill or strategy? Yeah, well what you were looking at was normal mode, the're 3 more tiers of difficulty, and if you find all that still too easy for you, play Hardcore mode, where if you die, you lose everything and the character. Oh so you get to level 48 and die? Tough. Game over.
Maybe do some research before you actually make silly comments about how hard the game is and all that. It's all on the interwebz you know, taking that 30seconds out to actually search google, maybe you'll use your brain some time eh?
Sujah, Battlefield has one of the best multiplayers in FPS at the moment. And Diablo, is a HERO DRIVEN GAME. Your supposed to feel epic when you start out. Plus the Beta was super easy, and purely a training ground.
If you search YouTube for "Diablo III - Blizzard's Top Tips for Inferno Mode" you'll find a video released yesterday that should give you some inkling of what to expect in terms of end game. Sounds reasonably challenging :)
And as others have said before me, they were most likely only playing the first part of the game (practically the tutorial stages) on normal. The later difficulties are where the challenge starts. Normal is for you to experience the story, and to ease new players into the game. Nighmare to Inferno is where the fun lies. ;)