As you all know, I bought the Extended Edition of the Two Towers movie yesterday. I also watched it. I can tell you without any hesitation that this version is noticably better than the theatrical version. I really enjoyed this one. It had much better continuity and the story just seemed more complete. Obviously with 43 extra minutes of footage you can really do justice to a lot more of the material. If you haven't seen the theatrical release or if you haven't read the books before then I definitely recommend you try to watch this Platnium Edition.
In addition it is awesome to learn about the processes that go into making an epic film of this magnitude. Sexy. The special features on the extra DVDs are perfect for gaining this insight into Peter Jackson's world as he was creating movie magic. This edition only costs $38 (at Walmart anyway) and is well worth it if you are a fan of the movie. There is a gift set version that is available for $81 that includes a statue of Gollum and an extra DVD (for 5 in total) that discusses in greater depth Gollum's character and how they created him. I'm not sure if that is reason enough to double the price, but when I got to Walmart yesterday at noon there were three missing from the display, so I guess some people thought that a Gollum statue would be a good thing.