I think Brissett is good. I think he has some starter qualities. I don't think he's good enough though. I think he's the exact type of starter you are OK having but always looking to upgrade.
This of course comes with the disclaimer that I am willing to give him this entire season to prove otherwise. We haven't really seen him in highly competitive situation in the last 18 months or so I realize he might have improved beyond what we saw last time he played regular season games.
My biggest fear is that we get stuck in a situation of having a Mariota/Dak/Dalton type at QB who is good enough to give you glimpses of hope but over the long haul you are doomed to mediocre play at the position. And this is the position where you can least get away with mediocre play at.