Sure.
I brought up Hand Shakers earlier but I don't intend to claim that Princess Principal is as visually repugnant as that series I only drew the comparison because both shows feel like they utterly fail to provide visually cohesive worlds. Where as Hand Shakers takes that in the most garish possible direction, Princess Principal instead opted to aim for a far more washed our variation on the same.
If anything, Princess Principal's major visual problem is that it is
too cohesive. It has a very narrow color range - lots of blacks and yellow-reds - and thus can feel a bit monotonous in how invariable the color palette is. I would prefer a color design with more spice.
Due you notice anything that stands out in the below shot:
I don't know about you, but my eye gravitates first to that ruby red sofa, then those green and purple rocks, and finally to that blood-red valve in the top right hand corner. Why? Because they're completely incongruous with the other colours in the shot. There's a strong tonal affinity between the colours of the characters clothes, an affinity which extends to most of the background art such as the brick walls and glass cases. There's no good reason for the sofa, rocks, and valves to be in their own separate colour universe - they aren't plot or character relevant, so what's going on with them? It just reveals that the image is nothing but different layers of visual art, created by different people, slapped together by yet another person and apparently not colour corrected by any kind of colour editor.
My eye first gravitates to the black blindfold myself. At any rate, your color criticisms of this shot seem misplaced to me. The red of the couch and the valve, while a bit stronger in shade, still match with the red of the brick wall and the general red hue of the setting. The green and purple rocks provide a moment of relief from the overpowering red which I appreciate, while still being muted enough that they don't really stick out in the overall image. While the production here isn't as highly refined in composite as the highest-tier of anime, such as Bungo Stray Dogs or Fafner Exodus, I can't see the color design as incoherent.
There are plenty of other visual issues worth discussing beside colour. Take, for example, the very first shot of the entire series:
What's with all this Crest of the Stars-esque shit digital noise? I don't understand why the art director thinks 19th century photography = a blurry, vaseline smeared mess? Obviously some of the photographs were not as sharp, and you certainly have imperfections in lenses and other artefacts, but they don't resemble this visual garbage. Why are you trying to hide your art under so many bad layers?
Oh well, at least this shot above is a little better, because it at least attempts to more accurately portray a family potra-
Oh dear, what's going on in here? If this opening sequence is attempting to emulate old time photographic conventions with any kind of verisimilitude then they should not employ jarring modern techniques like zooms and canted angles. Pick one visual style - don't attempt to mix and match in such a sloppy manner.
This is being too much of a pedant. While this expository sequence, as well as the brief memory flashbacks of Ange later on, uses artifacting to create an early 20th century ambiance, it seems silly to criticize it for one shot that may not be "historically accurate" in terms of what an early 20th century filmreel would have looked like as it describes a steampunk fantasy world. Moreover since this particular character is important to the story, being, I believe, the princess involved with the spy agency, it makes sense to single her out with the strikingly different shot to indicate her importance. Plus this shot is swept away with flames that burn it up, which is a visual technique that also would come from outside the "world" of an actual filmreel. If you need a real-world analogue, imagine that we're looking through the lens of a camera which is pointed at a separate projection on the wall as the film is being burnt up.
I brought this particular shot up earlier, but now that I'm being more critical I want to explain what's wrong with it. Clearly the imagery of a women perched atop a ledge that overlooks a sprawling a metropolis is reminiscent of Ghost in the Shell, especially as the women here also jumps off her perch in what appears to be an extremely reckless manner. What this particular re-creation fails to get right, however, is just about every element of what makes Oshii's shot powerful. Lets take a look at the original:
Did Oshii take out a patent on women falling from a building? If anything, this sequence riffs more on Gravity Rush, the video game, than Oshii's Ghost in the Shell movie. The character isn't supposed to feel threatened by gravity - she's in control of it due to the Cavorite orb she's using. This is establishing Ange as a self-confident character who can freely move through the insubstantial city.
Why does the character and the background art look like they're from two different worlds which shall never meet? (this is a huge issue in numerous scenes).
I don't think this is an issue in the image you highlight, but as I alluded to earlier I do think the composite is lacking polish in integrating different elements.
Why is half her face out of focus?
You might not have noticed this, but applying this kind of depth-of-field effect on facial closeups has actually become a common photography technique in current anime productions with some photographic ambition, such as Showa Genroku Rakugo Shinjuu S2 and Konosuba S2 at Deen or Sound Euphonium S2 and A Silent Voice at KyoAni. While I don't know the specific reason for using it in all circumstances, the interviews with KyoAni staff I've read say that they often use depth-of-field to create a hazy atmosphere, to make an image feel less solid and more touched with nostalgia or a heightened emotional state. That would fit with this image, in which Eric is getting emotional upon hearing Ange narrate her past tragedy.
Why is the one moving chair that they had to animate in this scene a completely different visual design to the all the static background chairs?
There probably wasn't an attempt to closely coordinate chair design between the animators and background artists in this scene, but then it's not that unusual to have different kinds of chairs in the same room.
Why employ all this horrendously busy wallpaper in your background art?
I've seen wallpaper with similar styles in early 20th century homes, so I assume it's another attempt to evoke the time period.
Are they in some 90's 1st person maze game?
I can't understand what you're talking about here.
The rim lighting here is disgustingly ridiculous. Are they on stage?
Yes, they are on stage. Metaphorically, at least. I, at least, appreciate the rim lighting that was present through this entire climatic scene. I think it's particularly effective in a shot like this:
Gross, purple lens flares are distracting.
Personal preference, of course, but I can see the reasoning for a disquieting lens flare like that in the shot in which
.
I'm not going to say the production of Princess Principal is flawless, as it certainly is not, but I do think many of the criticisms you make here are unreasonable.