First and foremost, an excellent dose of good fun in an (alternate) period piece. Not a huge expert on dress and style of the times, so if there were any deficiencies to the artist's portrayal of the period, I sure didn't spot them... and you've got to love Batwoman actually using a baseball bat to fight crime.
However, I did find it interesting that this is definitely an alternate history in more ways than one. Not only is it a superhero universe with a Gotham City, not only is it alternate to the main DCU in terms of period and (as the preview revealed) Batwoman saving the Waynes from Joe Chill... but the captions specifically call the year out as 1940 at the same time that there are references to lots of men being gone to serve overseas in the European theatre of war, leading to Rosie the Riveter themed billboards and the women's baseball league and all that. Guess this version of the US didn't need the impetus of Pearl Harbor to decide to enter the conflict directly as opposed to through Lend Lease and similar military aid programs...