When the series started, I thought it was a bit corny and avoided it for a few episodes. But towards the second half of the season, I was pretty tuned in as it got pretty good. Let's just say "Arrow" became the red-headed step child that The Flash was supposed to be. The Finale of The Flash was pretty bad ass.
I think that the black hole Barry is trying to close will probably spew out some famous/infamous villains and heroes into the current Universe. For instance, like Caitlin Snow, I don't think she'll ever turn evil because she's too liked in the show, but I do think Killer Frost will some how find her way to the current Universe. I also think we'll see a few different Flashes along with Barry.
Anyways, the show's writers and producers can do just about anything and still satisfy everyone by using the multiverse argument. I think the comic junkie in all of us, just wants to see all our favorite characters come alive from print to the screen. I think DC is pretty smart for slowly building us up for future Justice League movies.