Untrue...I am one of those people who spent countless hours playing each & every iteration of Ninja Gaiden (on every difficulty setting) and honestly the camera issue is a very very minor nuisance...all it takes is one button to reset the camera behind you...it isn't even half as big of a problem as its advocated.
The difficulty comes from the enemies who actively block & attack at each chance they get, its brutal like Demon's Souls where one wrong move means losing a major chunk of health. Sometimes its hard due to the cheapness like projectile spam in NG2, but that game is still nowhere near as hard as NG Black & that game didn't had cheap projectile spamming like NG2. The only game which I ever found to be even nearly as challenging as NG Black was DMC3 & even that game had many enemies which were slow & let you hit them.
I will always rate it like this DMC=NG > Bayonetta > GOW >>>Heavenly Sword
P.S.[Nothing like clearing a horde of enemies with Lunar's 360 or Scythe's ultimate technique ]
They will only respawn when you get back to an area & not all area will have respawning enemies.
Also you are required to shoot the archers before you cross using the hang rope, there's just two of them & you already have the bow by then...I'm surprised that you mentioned such thing as a game flaw & not your own. Majority of the game is spent killing fiends who don't use incendiary shuriken, rocket launchers or any explosives.
My thoughts exactly.