Personally i think the gameplay is a lot better than the first Bioshock.
Like you said, on hard difficulty the level isn't littered with health and mana pick-ups around every corner.
What i do miss however, are the different types of ammo and the ability to carry more than two weapons.
Hell, you had different ammo types in System Shock 1 & 2 which came out long before the Bioshock series.
Speaking of the hardest difficulty, couldn't you unlock it at the start of the game by doing the Konami-code?