Klaatu is an exceptional character only for the fact that he is the only character besides the main ones who really had two different outfits - the "regular" one and the skiff guard outfit. Now, granted, there was more than one of his race there, so it could have been a different "Klaatu" as well.
The Klaatu character came with a bladed force pike. Since we never really saw it in action, we can only guess he used it as a cudgel and a pistol. His loin cloth was also one of the few actual soft goods used in the original figures. The loin cloth came in two variations, thicker and thinner. Some Klaatus also had tan arms. The card back came in only two variations, one with a mail-away Emperor offer and one without.
Why should you get this figure? Five reasons:
1. Klaatu's name was inspired by the movie "The Day the Earth Stood Still," where the main character utters the phrase "Klaatu Barada Nikto" to his robot. This phrase was used again in other popular media, most notably a couple of scenes in "Army of Darkness" where Ash forgets the words and unleashes an undead horde. Ah, good stuff.
2. Because of you need this figure, plus Barada and Nikto, to complete a "set." In the later 1990's line they were offered as a 3-figure set.
3. He came in two outfits, so you might as well get one of them.
4. You have to throw someone down the Sarlacc pit.
5. That alluring loin cloth. I'm not gay, but if I were...
Wooof (his real name) is a Kadas'sa'Nikto was a pilot for Jabba's many spacecraft. He was killed when Jabba's sand barge was blown up.
Want more? His Wookieepedia article
91st in alphabetical order