I played Hardcore quite a bit in D2.
(Latest characters i didn't delete after last i played ladder finished )
And a ladder screenshot to prove i'm legit :]
To answer OP's question, in D2 you had different titles for clearing a difficulty, you name was written in red and your character was showed in ''battle stance'' instead of ''town stance'' in the chat... that was about it. Will probably be similar in D3.
Hardcore is extremely fun for me, but i definitively get its not for everyone. Playing hardcore imo does make you a much, much better player though, specialy when you go trough Hell. Everything needs to be calculated and you need really good reflexes to stay alive too. You must absolutly plan your spec right and keep survivability in mind instead of just spamming damage talents. Complete rejuv pots are also your best friend and you learn quickly to start crafting them with the cube even in normal.
I don't know how hard D3 be, but it will most likely won't be as bad as D2 was. Things like Iron Maiden preventing melee characters from playing some parts of the game on Hardcore, or Burning Souls that could just global you before you even react even with maxed resists unless you had Tgod on you shouldn't happen in this day and age of gaming.
I'm def pumped for it :]. I do plan to get a softcore character to 50 asap though to be able to profit from the PvP aspect of the game, but my second char will most likely be hardcore.
---------- Post added 2012-01-13 at 05:22 AM ----------