With these possible new designs, I'm very... uhh...
I think they suffer greatly from overly-humanized faces, which have been mentioned throughout the thread. The muzzles are very snubbed, the eyes are on the front of the face, and they have really human-esque face structures in general (especially the jawlines). It doesn't look too bad in the prancing vectors, but with the faces on the front, it's... very apparent. G4 had stylized faces and short muzzles, but the muzzles were still clearly just that, while these ones look like they have snouts and human chins. I was really hoping G5 would resemble the
rumored leaks from years ago, but it seems like they're continuing on the "let's not make them look like horses" route.
The irony of Imalou (who I actually do love as an artist) possibly influencing these designs is that I think she also played a role in designing Sisu (from Disney's upcoming
Raya and The Last Dragon), who has been criticized for having an overly-human face. I think it's sad that many animal characters are now being designed further and further into looking like either people or bizarre humanoids. There's so much charm and variety with animalistic designs (look at The Lion King, Brother Bear, Bambi, etc.), but many properties are really pushing for chibi/humanized faces. It's especially evident in ones that've been around for a while, MLP being an obvious example.
But faces aside, I wish there was more variety in the color pallette of this main trio. Of course there were pinks and purples in the Main Six, but aside from Pinkie, there was a good contrast of colors between them. Twilight is purple and pink, Applejack is orange and yellow, Rarity is white and purple, etc. The placement of these colors was also varied: if one pony had a pink body, another had pink hair. Even Pinkie had a lot of contrast between her hair and body.
With these three, their palettes all contain nearly the same two shades of purple/pink and they're on the same body parts. The colors seem desaturated overall and having dark purple outlines on everything makes it look worse (but seeing that they're CG, this might only apply to the vectors).
Nothing about their designs really communicates their personalities, while there was a clear visual language in G4. I like the addition of hoof feathers, but I'm not digging the distinction between the bodies and the horns, wings and hooves. To me, the designs resemble pony bootleg toys, namely Filly Funtasia, and if there wasn't a clear indication of the MLP brand here I genuinely would've assumed it was something along those lines.
I don't know the validity of this info, but the alleged names of these new characters (Izzy the unicorn, Pipp the pegasus, and Sunny the Earth pony) are weirdly... human? In a universe where there are characters like Rainbow Dash, Sweetie Belle, and
Fizzlepop Berrytwist for God's sake, it feels weird for main characters to have such a short and plain names. Even G4's "Pip" was short for Pipsqueak.