My thoughts on why this show couldn't stick
Spoilers ahead!
Flash Forward had a great premise, there was so much to work with. But I could tell from the pilot that it wouldn't live up to its potential because it lacked something very important - subtlety. Everything from the show's score to the acting were just so heavy handed. FF gets compared to Lost a lot and in this aspect, it could have taken some notes. Lost was successful in large part because the creators knew how to keep people hooked and suck them into the world of the island. They made it feel believable, made us feel like we didn't know what the hell was happening right along with the characters. (I'm not saying I wanted FF to be another Lost, which did have its flaws too, just pointing out what one show did right). FF on the other hand opened with this ridiculous car chase, complete with loud and unnecessary "suspense" music. The scene of chaos after the blackout felt forced and melodramatic. Then right after it we're thrust into this FBI drama. The very premise of FF meant that it had to be big, it dealt with a global catastrophe. I think they overshot and tried too hard to make it feel epic.
The sub-plot about having a blank FF vision and Dem's death was so beaten into our heads over and over, that by the time it came I frankly wanted him to just die already. Then amazingly they used that to go into a Final Destination plot. Just...no. Some of the acting was painful. I normally love Joseph Fiennes but he seemed to go more manic and cheesy in his acting as the show went on. Maybe it was just the dialogue though. I won't even get started on Dem's fiancé or any of the "villains".
The other flaw in the show goes hand-in-hand. The directors/editors were constantly insulting the intelligence of the audience. I understand the need to appeal to a wider demographic but they needed to realize that this show would only ever appeal to an audience who actually WANTS a cerebral experience. Instead, they threw in the same footage of a character's flash forward for every single revelation. As though we had forgotten that Mark is cradling a flask throughout his entire vision. I will give them some credit for going fairly in-depth into quantum physics later in the season, but at the same time it makes all the repetition seem even worse.
I really wanted to love this show. But every time I could feel myself really get into it, they would throw in someone/something like Flosso or repeat a line of dialogue for what felt like the dozenth time.