Witch-King

I couldn't agree more, and it was just too easy. He didn't present any challenge for Eowyn or Merry.

If I remember correctly, the Witch-King died the same way in the books.

Huge Buildup?

He was only given prominence in the middle of the the 3rd movie as Gandalf narrates how Sauron has embued TWK with more deadly power to represent him in his attack on Minas Tirith. The ensuing battle shows how treacherous he has become and he killed King Theoden.

If the Witch King was hyped up in Fellowship of the Ring then I'd get your point, but he wasn't so there's no real letdown

Yeah, well the whole thing with Merry, Eowyn, and the Witch King was one of those things bound to work better on the page than when filmed.
Because in a book you can *say* that Merry is fooled by Dernhelm, but you can't fool a movie viewer by by shoving hair under a helmet, so the whole dramatic identity reveal thing had to be dropped. Without that, all you have left is a short confrontation.

Also, they cast such a fragile little thing as Eowyn that you can't believe she could lift that sword, much less kill something with it. The Eowyn of the book was described as a tall strong sheildmaiden, eager to ride out a kick ass, and able to pass as a young man.

That was terrible, and it only gets worse each time I rewatch this trilogy.

Sauron has yet to reveal his deadliest servant, yet Angmar was present in all three films, and there were many witnesses each time, did he even kill a single person other than the poor Frey Gatekeeper at Bree, those Gondorian soldiers on the wall of Minas Tirith, and poor King Theoden?

Then when the Riders of Rohan show up in this film, Angmar disappears never to be seen again until well after Rohan plowed over a hundred thousand Orcs, then he has a terrible battle scene with Eowyn, gets stabbed by Merry and just stands there on his knees while she drives a sword into his face, good grief.