It's not the crime-fighting stuff that makes Flash a shitty character. It's everything else, especially how he acts with everything in regards to Iris. He's at least in his 20s, too, so he's not that young.
I get that a lot of the stupid stuff he does is driven by the stupid shit every superhero character does. Most of his problems are caused by himself; he needs to tell Iris he's the Flash, at least, and anybody else he gets close to should know as well. Iris is already in danger and that's been proven by her being attacked for her "connection" to him from the writing. There's no benefit to not letting her know who he is. He also needs to apologize for what happened in last night's episode, but there's been no suggestion from anybody that he do so nor has there been even a hint that it'll happen.
I haven't watched many of the superhero shows because they are often very badly written, but this is turning bad a lot faster than even Smallville did.