Judging by the "Kingdom of Heaven: HBO First Look" special, it'll rival LotR (perhaps, dare I say it, surpass?) in many ways.
The CG stuff looks amazing. As good as that was for the LotR films, once you see a troll, oliphant, or nazgul, or even an orc, it does jar you out of the pseudo-reality. The bits of the seige of Jerusalem they showed in the special were incredibly impressive.
They made period equipment (armor, weapons, etc.), so they say, for about 2,500 people. Of course, for this (as opposed to LotR) they had a real period on which to base their equipment. Same holds true for the seige weapons.
They, apparently, set a new record for the most people set on fire for a single stunt (56 people).
I've got to say that I felt the LotR films set a standard for movies similar to this (epic battles, fantastical, whether fictional or true, stories, etc.) that I thought would not be topped or even met in my lifetime. Movies such as Arthur, Troy, and Alexander had me believing that would be true. It seemed no matter what combination of cast, crew, director, producer, effects department, etc. that was brought together, such magic would not be available in significant quantity to even come close. It looks to me like Kingdom of Heaven is going to prove me wrong.