Hello Chut,
I am happy to say that my Master Ultra Thin Moon 39 arrived today from my authorized dealer - I am wearing it as I type this. I chose stainless steel, and I can say you will not be disappointed with the "dressiness" of the watch in SS. I am a prosecutor and wear suits on a daily basis, and the watch is perfect as a dress watch. In fact, it is stunning! I hope to post a wrist shot soon! The watch is gorgeous, and exudes class.
By the way, this is my first post here - the MUT Moon is my first "real" watch. I also own a quartz Tag Heuer 2000 (my first watch), an Omega Seamaster (also quartz - still kicking myself for not buying an automatic), a Hamilton Jazzmaster Viewmatic and a Longines Master Collection full calendar chronograph with moonphase. All were much more modest purchases, but they all increased my interest in fine watches. As I came to learn more about watches, though, I became enamored with JLC and was finally able to obtain one of my own. I was not disappointed when I opened the package!
Good luck with your decision. You will not be disappointed either way, regardless of which you choose.