- Audience-Alienating Premise: Some people will be reluctant to play a game featuring 14 year old girls in Stripperiffic outfits.
- Contested Sequel: At least in the West. The story is generally viewed as much better than the last few games, and the many gameplay improvements earn the game plenty of fans. However, it's also received quite a bit of criticism in the English-speaking world due to its large amount of expensive DLC (which is viewed more harshly in the West than in the East), a translation riddled with typos and grammar errors, and the lack of a dub (a first for the localized version of an Atelier game).
- Guide Dang It!: The ending requirements are rather obtuse even for Atelier standards.
- For the the shop ending: getting 100,000 coll in the end is not that hard; the problem is that triggering one of the events to incur it requires dipping under 10,000 during the last chapter, and it's very possible that a sufficiently savvy player would never allow their savings to get that low. The game gives you no indication that this is a requirement. Furthermore, the game doesn't give you a goal in the menu once you've hit 50,000 coll, and therefore you'd have no idea that 100,000 is the actual number required to trigger it.
- For the painter's ending: triggering the first event for it requires synthesizing all the environment-changing paints and another of the restoration paints...even though up until then the restoration paints had all been story items used only once, so there'd be no need to make another one.
- The requirements for the true ending are still rather obscure, because it's difficult to determine whether it requires unlocking all the endings, fulfilling all ambition notes, or getting maximum score on all the assignments — the only consensus is that there's some connection, and yet people have unlocked the true ending by not doing one or more of these.
- Hollywood Homely: There's an event where Lydie and Lucia say that Roger is becoming less attractive with age, even mentioning warts, but he's a gorgeous biseinen with nary a flaw to be seen.
- Les Yay: Sophie and Plachta are pretty much all but stated to be a couple by the end of the game. Their event ends after Plachta realizes she wants to be with Sophie. The two affirm that they are each other's happiness, and promise to grow old together. And Everyone Can See It, with Lydie, Sue, and Firis conspicuously giving them time alone together after Plachta gets her body back. You can think about the implication of that on your own.
- There's some hints that Ilmeria might be in love with Firis, complete with almost mumbling out a drunken Love Confession to her. There's nothing on Firis' side to suggest it's mutual.
- Surprisingly Improved Sequel:
- After Sophie and Firis, the Mysterious series had come to be a somewhat polarizing one among Atelier fans, with players citing reasons such as comparatively uninteresting characters, stripped-down combat, tedious gameplay pacing, among others. Lydie & Suelle, in contrast, heavily simplified the more obtuse parts of the system and is completely packed with characterization events, resulting in much higher critical approval.
- In terms of its position as a series finale, it's also considered to operate as a far more satisfying conclusion than the last one, Atelier Shallie; whereas Shallie was criticized for ending the Dusk trilogy on too much of an open-ended and inconclusive note, Lydie & Suelle goes in completely the opposite direction and goes out of its way to bring the Mysterious trilogy's themes and loose plot ends. It's also considered to handle the dual protagonists in a better way than Shallie or its predecessor Escha & Logy, in that rather than requiring the player to go through two barely different-routes in order to get all of the story content and Golden Ending, this game allows you to switch protagonists anytime and focuses on a single story involving the two of them.
- Tainted by the Preview: The announcement that the game's Western release would, for the first time in series history, not have an English dub, has caused many fans to reconsider their purchase. Some are especially annoyed that the previous games of the trilogy have a dub, making it feel inconsistent and wishing that they would at least finish the Mysterious series with a dub before switching to subs only, while others simply refuse to play any game without a dub.
- Unexpected Character: The Puni from the Exam in Atelier Firis returns as an NPC, an is terrified to see Ilmeria again. Mainly due to being used as a target for several end game bombs.
- Win Back the Crowd: Due to the aforementioned criticisms of the Mysterious series and Firis causing the franchise to have a huge tank in sales after Sophie, upon Lydie & Suelle's announcement Gust immediately tried to invoke this trope by promising that it would be different from prior entries, to the point where they released a free demo of the game and showcased an entire event of player testimony on its improvements. Ultimately, while the final game ended up critically praised for indeed fixing many of the issues from the prior games, ultimately ended up with 180,000 sales by April 2018 off word of mouth after a poor first week of sales.
YMMV / Atelier Lydie & Suelle: The Alchemists and the Mysterious Paintings