For mine, it's not so much the thirty-seven endings (which, as already pointed out, are in the book anyway). It's more that, in the film, the character of those endings cross that fine line from sentimental firmly into mawkish.
I found the second film has the same problem, albeit to a lesser extent.
FotR is the only film I really enjoyed. Yes, I realise that I'm in a tiny minority.
It's kind of gratifying that people are no longer entirely uncritical of everything that Peter Jackson does.