This is less likely to share common ground, but I... actually liked Flip. Rather, I liked the idea of Flip, and his scant few moments of focus for him were something I enjoyed. I liked his debut Duel, for starters, and the two rather isolated moments during the lead-up to Astral's rescue and right after were also good for me. In fact, I was rather touched at Flip for the memorial he made for Astral, and his VA's delivery of those lines were super effective, especially given the circumstance of the character's character.
Flip's problem is that they didn't do nearly enough to do the character's potential justice. This was, alas, a recurring issue for anyone who wasn't Yuma, Shark, Kite, or the writer's current favorite antagonist. (Though it is still early, VRAINS seems to be following a similar bad habit, what with its over-reliance on Yusaku and no one but Kusanagi or Ignis getting anything related to consistent screentime, with the former being someone who's a non-Duelist in a show featuring Duels whom we don't know nearly as enough as one would think would be know with the screentime he's consistently allotted. [In this sense, Ignis is Astral and Kusanagi is Tori.] Furthermore, Go and Blue Angel both awesome and cool characters, from personalities down to aesthetics, drop in and out of the story to a frustrating degree, meaning they only have a patchwork knowledge of what going on, and Noaki, another character with potential, is... being squandered. Almost tantalizingly so.)
Speaking of Tori, she's kinda a hot button topic, so I won't speak on that. Also, regarding Naoki again, I see him as the perfect opportunity to due a genuine Joey expy with Naoki's growth as a Duelist and character. They have to use him, first. Beyond the awesome but extremely limited single true focus episode in going on 50. The way he "opted out" of the arc may lead some hope for him later, but it could also be used as an excuse not to use him in earnest again, so it's a little worrying.
Lastly, I sorry you don't like the merging. I think it's super cool, though, and hope they don't miss the chance to go the, in my eyes, obvious enough route.