3940 is very thin (well... I'd say it is one of the thinnest perpectual watch ever made....please correct me if I'm wrong). Its diameter is "small" with today's "standard" (when compare with Panerai/Santos 100).
With its "small" size, it is kind of understated (especially with PT/WG case).
On the other hands, its face is "iconic" for PP. In the official PP magazine, it mentioned that 3940's face is the most well known "iconic" face for PP.
These characteristics may be good or "bad" depends on what you want
FYI, PT does NOT come with a see-through back.... it has only solid back. For WG, RG, and YG, they all come with both see-through back (attached with the watch) and an extra solid back.
Movement-wise, it is superb.