First, the civilian forms for Mirai (top) and Riko (bottom). Very cute - I like Mirai in particular, since she looks like she could be related to Haruka with her big, wide eyes. Maybe they could be cousins or something. Riko's kind of serious demeanor is interesting, too.
As you can see, the two girls look visibly older as Cure Miracle & Cure Magical (respectively), but only by a year or two. Miracle's design has drawn cries of her being an "Ichigo rip-off" (in case you're unfamiliar, they're referencing one of the mains for Aikatsu!), but really, the most overlap is in the "blonde wearing pink" color scheme & that applies to a lot of pink Cures. Her dress is cute, but I think it's also kind of generically cutesy, which is probably another source of the "rip-off" accusations. Cure Magical's dress is a lot more unique - I especially like the capelet - but it's also a tad busy. I'm also the only person weirdly okay with her bat-wing hair.
It's worth noting that I am among those disappointed that the girls' witch hats are so very tiny. I know their civilian school uniforms have standard-size witch hats, but a traditional magical girl with a normal witch hat as an accessory would look pretty amazing. This way, though, they're tiny to the point of being silly. Well, this is Precure we're talking about...
One of the "hooks" of this series is that the girls have gemstones that allow them to transform into Ruby, Sapphire, & Topaz variant forms. I hope these are used more effectively than the form changes in Happiness Charge Precure, which looked really awesome but were only utilized once or twice apiece & solely for crowd control.
First, there's the Ruby forms. Not sure what the overall theme is besides the striped bows, but there's a common hairstyle for each form change. These are probably my least favorite of the designs; Ruby Miracle just looks sort of generic & Valentine's-y, while Ruby Magical has those awful, awful garters & looks like a Christmas-themed gothic lolita. Pigtails are cute for both, though.
Next is the Sapphire form, which could either be sky themed or ocean themed and has a much softer, more toga-esque feel. Both look pretty cool, but I like the colors in Sapphire Magical's dress a lot & I also dig Sapphire Miracle's elaborate ponytail.
Finally, there's the Topaz form, which is probably my favorite. Its theme of sweets is pretty apparent, and it has the signature Precure bonkers-ness that I enjoy. Also, finally, Cures with braided hair! The bazillion hard candies on Topaz Miracle's outfit are pretty cute, but I adore Topaz Magical's sublimely stupid flan hat and pudding-themed skirt. It's ludicrous and I love it.
So yeah, I'm looking forward to Maho Girls Precure. Go! Princess Precure was surprisingly good even with a mid-series creative shift (which worked, because it meant removing Shibata), and it looks like they're going with an all-new staff whose worked on all of the past seasons in different roles. It should be interesting to see where this season goes and if it's as much of a loving nod to both the series' & Toei's past as the announcement suggests.