Never played the NES one,
Allow me then...
-[tornado fang] you birds.
-Gets quite cheap in the last levels.
-[tornado fang] you birds.
-Yay I finally beat that really annoying last boss! Wait, it has another form?! Damn, oh well...*game overs* WTF DO YOU MEAN I HAVE TO GO BACK TO THE BEGINNING OF THE LEVEL INSTEAD OF JUST THE STAGE I WAS ON LIKE IN THE REST OF THE GAME?!!!!
-You can't just jump into the pits instead of taking the ladder even if there's a ground below it or else you'll die.
-[tornado fang] you birds.
And yes, if you've played the game you know those 3 "[tornado fang] you birds" (now 4) is really, REALLY necessary.
Castlevania: Order of Ecclesia or Judgement
Let me do Judgment since I have actually spent quite a bit of time with it.
-The character designs, while I personally like most they are a deal breaker to many people.
-Kinda shallow fighting game, the characters need more attacks or at least variations in their standard combos.
-Hypers are too strong and long and the meter builds really fast so you'll be seeing them frequently.
-Castle mode could've been much better, right now it gets kinda boring fast.
-Only time we'll probably ever see Aeon =(
I still say it's quite a fun game if you give it a chance and [tornado fang] the haters though.