That's exactly what I mean. It has a lighter tone, so you write it off as childish and assume they aren't going anywhere with things instead of looking any deeper. If there's more to your argument than that I'm not seeing it.
The flashbacks work for Arrow because he had a long period of training and isolation that ties directly into the season plots. That's great there, on Flash the story is in the present and about the future, constant flashbacks would only distract from it. There's also just no way to do the Flash for a full season before really getting to the point of being a superhero. Different characters, different themes, different tone, both do what they do well. It's a good thing, for the most part.
You make a lucid point, I suppose. I guess I was expecting more of the same from the Flash, expecting it to be dark and brooding, and perhaps the lighter tone is a good thing (They even make the comparison when Oliver and Barry meet). The depth of the plot, however, isn't showing just yet except in small hints. I would have held off on the 'metahumans' for a little while, invested more time in building up Barry's character, as well as his love interest. I have to admit that that is the part that I detest the most. Introducing the metahumans a bit more gently, as well as the whole costume, the name and the 'team'. They crushed all that into the first episode, filling the rest of the episodes with angst, Barry crushing on his love interest and acting all weird that she is with someone else (One of my least favorite plot points ever, btw) and 'with great power comes great responsibility', slipping in hints here or there that there is something bigger on the horizon but not really building on that. Just hinting at it. They pushed the fact that Wells is something other than what he claims in the first episode, and resorted to just having him cackling at the end of every other episode just to remind us that, yeah, he's got a secret that he isn't telling us.
The whole revenge over dead mother thing feels rehashed from every other superhero movie, although I have to admit that him wanting to prove his father's innocence by catching the Yellow blur is a fresh and welcome aspect.
I don't dislike The Flash. I've been watching every episode, but for me it just lacks the storytelling that Arrow had, as well as a few other elements.
I've never watched Smallville, though. I am not Superman's biggest fan. And I like the higher tech but less super power guys, which is why one of the very high points in the Flash for me was Wentworth Miller's character.