So after playing through the beta with 3 different characters, I've come to the conclusion: this is not Diablo 3. I guess it's a good game, however for Diablo veterans you have to go into it knowing it's not what you want. The only thing that makes it "Diablo" is the name, the fact that it's still an ARPG, and the storyline. They should have just called it something else like "Demon Slayer" and created a new story - then it would have been received better by Diablo veterans as they wouldn't be expecting Diablo.
The problem is, for me and many other Diablo veterans, we're searching for nostalgia... If you want to feel the same feeling you had playing D1 and D2, you'll need to go elsewhere, because it is definitely NOT D3. Maybe give Path of Exile a try, it is clearly more true to the Diablo series than Diablo 3 is itself. For non Diablo veterans or those who never really got addicted to the game, you could like Diablo 3, try it at least before the open beta finishes.
Remember playing hardcore and the adrenalin rush from near death encounters? Remember the thrill of the game. The excitement experimenting with new builds. Well that's all gone in Diablo 3. The dark goth look of Diablo has been replaced by cartoonish WoW influenced graphics that pretty much destroy that nostalgia feeling right from the beginning. The skill system is dumbed down, they took an already simple game and simplified it to a point where you feel like you have no real control over your character. You're just following a linear path, through the story and through the development of your character.
For all those who feel the same. Take a look at Path of Exile and Grim Dawn, both games look great in their own ways and they need your support. Grim Dawn has a KickStarter page going strong right now, and Path of Exile is accepting support through their site. You can actually purchase a Path of Exile beta key and try out the game, it's a great game. It may be a bit too cut throat, but still a great game that has a dedicated team improving it everyday. You might even get that Diablo nostalgia feeling you were looking for in D3 but couldn't find. Another ARPG to look forward to is Torchlight 2, while on the cartoonish side, it will still be far more true to the Diablo series than D3 is.
If Diablo 3 isn't satisfying your thirst for Diablo, look up: Path of Exile, Grim Dawn, and Torchlight 2.