Regarding the original post, yes, I agree, Nightfall in general seems to have a blatant issue with mission balance. Not each individual mission, but the fact that you can go from one mission that's easy as cake and you beat it first try, to a mission where you get totally killed in about 15 seconds, then back to another mission that's so easy it's boring.
Not saying that each individual mission is too hard, just that some missions require very specific skills to counter certain enemies/obstacles, and even when you have those skills equipped (which usually only comes if you read guides or play through the mission and die once to learn the hard way), it can still be tricky. That's alright, only you never know when to see it coming. You'll finish a mission that a blind monkey could do, only to be hammered into the ground the next mission. After you overcome the problem and finish said mission, you find that the next mission is back to blind-monkey difficulty again. lol.
Who here can honestly say that the final mission was the hardest in the game? I can think of at least 3 other missions right now that make the final mission look like you're fighting a big fluffy bunny of kindness.
As a whole, I love Nightfall, but it has to have some of the worst difficutly balance I've ever seen in a game. I can't for the life of me imagine how it all went through testing and everyone gave it a thumbs up, saying "Yep, this is all well balanced!". It seems like multiple mission teams were developing them all at the same time, and weren't communicating with each other on how hard to make each mission.