Kind of figured that when Reimu beat up Rumia in the last chapter. Unless you wanna drag this for another volume, it'll just be retelling EoSD.
Even as it was, it was mostly retelling Perfect Memento in Strict Sense.
Except Perfect Memento is very clear on Reimu being a much more easygoing character who thinks hard work hardly works and gets by on intuition and good luck. Which I like - that subverts a bunch of heroic shounen protagonist tropes, which SPELL played straight instead. The resulting Reimu is kind of... less fun.
I would've dug a darker and edgier take on the origin of the spell card rules, but outside of that first chapter, it didn't really materialize. Yukari just... comes in and solves everything. Nothing truly remarkable (or rather: unexpected) happened from chapter two onwards.
The author has done some great work with fully invented storylines featuring established characters (particularly Komachi in Shinigami Rows Her Boat) while paying careful attention to be faithful to the source material - and that faithfulness kind of became her undoing in SPELL. Once it became clear the manga was trying to connect all the facts about the vampire incident we knew from PMiSS together into a coherent whole, the outcome of every fight was effectively predetermined and there were no stakes.