I bought this game two weeks ago, and have really enjoyed it. All my attempts have been in Ironman mode, since I like having more of a challenge. Aside from some deaths in the first two fights, I have one play-through that ended with a death to the gnolls at the backdoor to the the orc/slaver fortress, and my last game made it all the way to level 20 before I died to the nasty undead ambush after that level 44 dragon.
It's been a while since I enjoyed anything as much as this. The combat system is fast and clean, with lots of options. The dungeon design is quite good, with plenty of nasty tricks - ambushes, wandering patrols, doors that shut behind you, and really smart AI. I was totally impressed when I saw a golem standing in the fire to heal, and then doubly impressed when, after try to block the brazier from another golem, it bull-rushed my wizard out of the way!
Roughly speaking, here's what I like about the game:
* Ironman mode, just like the old roguelike games
* Lots of detailed tactical options (grapple, 5' steps)
* Feels "clean and simple" like classic OD&D modules, without all the abusable prestige classes
* Fairly high difficulty in the early battles (L1-8), and at the end (L19-20)
* Old-school graphics and music (I don't care for the 3D rendering style or GUIs of NWN and other newer games)
Here's what I don't like:
* Quest rewards can't compete with crafted items
* Many buff spells become useless (e.g. Stoneskin, Blur), as they are replaced by permanent items
* Very late battles start to feel luck-dependent, depending a lot on saving throws
* Fighters are a little too weak relative to other classes at the end ("I can't touch this dragon, arghh!")
* Too much money floating around in the game after the slaver city
I also wish there were a few "hardcore" features/options to play the game closer to old 1980's games (memorized spells, need to bandage unconscious characters, more descriptive text to read, etc), but I realize I'm probably in a small minority of people who want all that.
I think for my next play-through, I'm going to try avoiding taking any crafting feats until I hit level 20. That should make the giant-based stages of the game a bit harder, and make quest rewards feel more exciting. Alas, I don't think I'm good enough to beat the final few encounters without a full arsenal of crafted items.