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Finally finished it yesterday. Gotta say it was leagues better in term of storyline than the previous 3 pseudo-singularities. There are a lot less filler episodes than usual, instead we got "play" episodes which are fun in their own right. They build up quite nicely the mystery element early on instead of stumbling around introducing landscapes and people, a nice change of pace after Shimousa. While they don't try to hide the new servants' identity much, that doesn't detract the story at all but instead helping me focus on the mystery at hand. Beside, after Moriaty and Columbus, I think we all get used to the "betrayal companion" shtick so they just drop that altogether.
For the gameplay, have to say while I was annoyed early on because of the power-down mechanic, the fact is that the difficulty of the fights in general are on mid to mildly hard for the most part so that's a no-issue. We also got a new class, Foreigner, which in its own right shouldn't pose much of a problem; it's just the boss basically being a ST version of Amakusa that almost wrecked me.
The OST and SFX this time is a big improvement for me from Shimousa. There aren't any track as memorable as Grandpa HYPE's, but they converse the atmosphere quite well. I especially like the eerie hanging noose sound.
The only bad thing that's worth mentioning at this point is the pace after chapter 7. Everything felt rushed, like the writer had ran out of time and wanted to wrap everything up as fast as possibe. If the length of the resolution sections had been expanded to double the story would have been much better in my opinion.