(Disclaimer: The following dissertation comes from someone that has yet to see Stage 1 in action.)
So I've been thinking about the issue of Cirno's sprite, and how some people have taken issue with it, but have been unable to properly articulate why. I admit that (a) I found myself disliking it when I first saw it as well, and (b) I couldn't properly articulate to myself why I disliked it either. After spending some time dwelling on it, I think I've realized what the problem is.
One of the many little touches I've been a huge fan of in these games is the design and animations of the boss sprites. In addition to things like waving arms, flapping wings, and wiggling legs, the sprites were routinely designed in such a way where you actually felt like you were squaring off against another person in a danmaku battle. Even in still images, their poses suggested obvious ways in which the sprites would animate to suggest movement around the battlefield (be it swift movement or lazy drifting), as well as obvious ways in which the sprite could attack with bullets, usually by having arms in various ready-to-fire positions that we've all grown accustomed to through Dragon Ball Z and countless other shounen franchises where people shoot energy from their limbs.
I look at the current Cirno sprite and see neither of these things. Back in EoSD and PCB, she would be leaning one way or the other, where a wing-flapping animation combined with drifting in the direction she was leaning made sense as a portrayal of movement, and she'd have one or both of her hands out a little in a way that attacking made sense. There is no obvious outlet for movement animation or attacking animation. Her attempt at perfect vertical symmetry has left both her body and her legs in an incredibly awkward position if she suddenly wants to move laterally, and having her arms akimbo does not lend itself to any sort of idea of where the bullets she shoots are coming from. Frankly, she looks superimposed on the screen, like you could take your cursor, hold-click her, and drag her across the screen like an application window with pose never changing and that's her movement animation. I honestly look at her and see nothing to suggest even how her pose would easily change to accommodate the needs to move and shoot.
Now, again, I have yet to see Stage 1 in action, so maybe there is a proper animation given to her. But just from looking at the stills that have been provided, I can't fathom what that proper animation could possibly be.