One thing that I think is a flaw in all versions of dnd, at least from a game design standpoint, is the early level difficulty problem.
Generally in games you want to start players off on easy mode, adn then scale up the difficulty as they get used to the game. But in dnd, the first couple of levels are actually "brutal" in difficulty compared to later ones, its very easy to die when your a first level character, much harder when your 5th level.
It makes sense narratives, a newby character IS more likely to die than a veteran, but it an oddity in game design terms.