A lot of the scenes were designed for pacing reasons... and a lot of the scenes that were removed were for pacing reasons.
I like the box-set, especially the commentaries that go with the extended version. I think there are four separate commentaries which include the main actors, then another with the director and writers and then two more commentaries.
After seeing the extended version of Apocalypse Now, I was wary about any version of any movie that has deleted scenes back in. I can see why some of those scenes were left out. But overall, the deleted scenes added back to LOTR do help to clarify the story a little more and overall the movie is as good as the original cut...just a bit longer.