FELLOWSHIP doesn't really need the new scenes, aside from one that sets up THE TWO TOWERS a bit better. They're nice and sometimes fun, but the only one that I felt was damaging to the pace was the White Council extended scenes. Even that wasn't too bad, since it did make Boromir's contribution to the scene more logical (there's something off about the cinematic version's scene of Boromir saying, "It is a gift!" without the EE's previous scene of Gandalf arguing with him).

Overall, I think FotR's extended edition doesn't work too badly and the pacing works if you take advantage of the disc swap to have a break.

THE TWO TOWERS is saved by its extended cut. The cinematic version is a near-disaster in terms of structure and pacing. The movie is lopsided, with Merry and Pippin vanishing for large stretches of time and Sam and Frodo doing the same. The EE gives both sets of characters some vital scenes back makes the story feel more balanced, as well as establishing Faramir's character with that superb flashback scene with Boromir and Denethor (which the cinematic version badly misses, as it leaves Faramir almost bereft of any kind of characterisation or character arc). Now the whole thing feels better and makes more sense. Bizarrely, despite being 40 minutes longer, it feels shorter than the cinematic version.

THE RETURN OF THE KING, on the other hand, is almost destroyed by the extended cut. On the commentary for FELLOWSHIP Jackson is saying that there's still stuff he left out because it disrupted the pace or didn't work tonally. On the KING commentary he's now saying how he doesn't like scenes but is just throwing them in because the fans might want to see them. The terrible 'pirate ship where half the production crew cameo' scene is a clear example of this and should have never made it into the film (actually, it should have been burned). Gandalf confronting the Witch-King sounds great, but in fact sucks and doesn't make any sense (and is less epic than the comparable scene in the novel). Aside from clearing up the geography of the Steward's tomb and the rest of Minas Tirith, and the nice scene with Frodo, Sam and the statue's head, there is nothing to recommend the EE of RETURN OF THE KING at all. And at over four hours, it makes the film just way too long.