I liked some of the art, particularly the kobold's face, the Yuan-Ti (prior to clicking for the base description), the displacer beast, githyanki, and umberhulk (prior to clicking on the picture). Each of the other pieces of art are either too inconsistent with each other (compare the art for the rust monster with any of the other pictures or poorly represented (especially the orc and giant).
Oddly enough the more I look at it the more I am beginning to think the rust monster picture is my favorite example WotC provided. Particularly because the style it represents is so enigmatic as compared to the rest of the monster art (even to the point that it is the same image when clicking the picture).
Of all the images though I must say the orc is my least favorite. At least with the 3rd edition orcs, their design seemed unique as a form of savage proto-simian humanoid. The 5e orc simply looks like an overly muscular rendition of the orcs in World of Warcraft. I personally feel that by mixing simian and porcine features with a slightly more realistic bodily frame would do wonders.
While there may not be "a default setting" it's worth noting that all of the modules created so far take place in the Forgotten Realms world and the Encounters adventures will as well.
Marv / Finarvyn DCC playtester (2011) S&W WhiteBox author (2009) C&C playtester (2003) Builder of the TrollBridge for T&T; Amber Diceless player since 1993 OD&D Player since 1975; Metamorphosis Alpha since 1976
"Don't ask me what you need to hit. Just roll the die and I will let you know!" - Dave Arneson