The extended versions ARE better, but mostly they put in details and scenes that are needed more to explain things to those who aren't intimately aquainted with the stories.

Here in the LA area, they've been running FOTR and TTT extended editions in theaters for the past two weeks leading up to the ROTK opening. I saw TTT this weekend, and it was worth the $9.50 to see the 45min of extra bits on the big screen. The same theater is doing a Trilogy event on Wednesday. 10+ hours in the movie theater? Yikes!