Made it to level 20, human sorc. Here's my experience for whatever it's worth:
It was fun and a real different way to approach and play the game.
I got to level 5 before I became a VIP and joined a guild. Didn't think I would do either. The xtra xp from monster manual and other sources for being a vip was very nice. Running quests n-h-e was just too much of a grind for me. Guild helped with buffs, especially running speed. One thing I would do is get a horse. I didn't and there were plenty of times I wished I would have put the time in.
Mostly solo'd although I tried to group at the start. You are putting your life into strangers hands though. One group I was in for Bookbinder, 5 of us went in on top and for some reason 1 entered on the bottom and promptly was incapacitated. The rogue rushed toward the bottom to try and save him and was killed by a trap. Time to exit and re evaluate groups. The last time I grouped was Red Fens. As I was just entering the wilderness area four group members raced by on horses and caused DA. I wished them luck and left. I was in some good groups as well though, you just never know.
Had a couple close calls. Was incapacitated in Chamber of Insanity and hireling healed me and also incap during Haywire Foundry carrying hireling soul stone towards shrine. A champ foundry engineer got me (I got him first tho) and got a lucky roll to survive.
Reached 1750 favor at level 17. I skipped lots of quests and 1750 favor can be obtained MUCH earlier. I was in no hurry as getting to 20 was my main goal so picking quests I knew was important to me.
Died twice. I've been playing this game a long time and had no idea the danger room on the ship existed until level 12. Innocently looking for the ah on the ship and just looking around and <ding>. Laughing about it now but why is that even on the ship in hardcore? Other death was in Undermine. Exploding barrel + exploding kobold + ice trap spelled my doom. Stupid death, I was going too fast.
Played mostly on elite until the end where I played on hard. Finished with Sharn, The Cogs, and Meridia quests last two levels.
I bought 4 rogue hires to help with trapy quests and a fighter hire twice (Club) for the last level as a security blanket.
I think I will retire this guy and start a new one. I'd hate to see this one die if I TR. I don't think 5000 favor or reaper is doable for me. Maybe I'll try reaper as that's what I usually play on normal servers, but I'll see. My hats off to those able to do reaper and 5000 favor. Impressive.
I will say I really have an appreciation for the lag deaths. I lagged a couple times at the end and was freaking out. That would have REALLY sucked to die because of lag. It's too bad nothing can be done for those who have gone through this, but it does make those extra lives that more important. Probably the worse aspect about hardcore is lag deaths.
Well I'm off again and start anew and perhaps TR the new toon...if I make it that far.