I missed basically all of season one, so I am not watching season 2 until I can catch up, but I am aware of some of the stuff happening and other things coming up.
I read a few interviews with the cast and crew and they were very insistent that this was going to be a "realistic" take on the DC universe and any other characters showing up would be viewed from that perspective. When I heard Black Canary was on, I asked a friend who is watching the show how they handled her abilities and he said she uses technology instead of any metahuman ability. So I am wondering how they are going to introduce the Flash. Is he going to be just some guy, perhaps using some kind of steroid that makes him run at maximum human speed?
I don't understand why DC's live-action projects seem almost ashamed of their comic book origins. They are obsessed with making everything "real-world" conceivable.
This seems to have changed with the success of Man of Steel and possibly the announcement of Agents of SHIELD.
Season 1, especially the first half, was dominated by this "make Green Arrow more like Batman, darker, more realistic, GRIT GRIT GRIT." It even heavily copied the Batman Begins soundtrack and had a very Nolan-esque tone, quite frankly it got boring fast. Towards the end of the season it started to feel more comic-bookish and Season 2 has definitely hit the ground running with the idea of a bigger DC universe to explore. The Flash, according to producers, is going to be THE Flash from the comics, Barry West, forensic scientist, some sort of accident turns him into the Flash, full on scarlet speedster with the red costume and everything. They've also name dropped Ra's Al Ghul and the Birds of Prey and Hal Jordan are rumored to be featured in the future.
I don't mind grounded, but season 1 of Arrow showed what happens when you go TOO grounded, the characters lose what define them and it's really bland. By what I meant above, Man of Steel's success finally laid the groundwork for the DCU in movies and the announcement and hype around Agents of SHIELD probably prompted DC/WB to consider what they have with Arrow. Let Arrow be DC's Agents of SHIELD, connect the movie and TV universes. This isn't confirmed by any stretch, for all I know they'll keep Arrow/Flash and the movies separate, but I think they have a fantastic opportunity to build Green Arrow and Flash on TV, then bring them into a Justice League movie with no needed introduction, save that for the characters that need it.