I'm slightly disappointed they killed him off but I thought the way it happened was fine, if that made sense. As in, the way he died was along the lines I'd imagined it'd happen in a series finale anyway.
Backstory got weirdly hyped up by some people on the crew when it turned out to be the most mundane shit ever and no different from the most basic prediction everyone made months before: Moon's wearing her current crown, so Toffee must have killed her mother. But I thought the decision to make the tapestry inaccurate worked well narratively: you literally can't have Moon be a super badass or former friends/lovers with Toffee or having made him a villain in the first place, etc., and have the story still feel as though Star's relevant to him at all. In that case, having it turn out he'd had a grudge against the Butterflys even before Moon and that she and Star had both suffered from his actions without really knowing him made sense. That "Demon Buster" poster with young Moon and Star facing Toffee turned out to be more accurate than expected, as both of them sort of had patchwork experiences with him that only add up to a whole taken together.
The real issue is that the Moon flashback where she faces him was done pretty badly. It doesn't come off as "Moon ruined his reputation and made him aware of his own mortality" so much as "wow, his soldiers were fucking cowards."