I can't say too much because of spoilers, but even by just playing for a short bit you'll see these two have immense love & care given to them!
Ability wise, I love how each one compliments another, and also feel good to use on a controller since I play primarily with one! Inazuma is familiar to me, thanks to both his homing bolt & barrier. The barrier in particular is familiar as it at first feels very similar to Gunvolt's Flashfield, but it doesn't fizzle in water & I really like the way shields alter it subtly. Aether is particularly special when you get down how to use her spells effectively, and I can imagine people will get in some insane speedruns once timings are nailed down for each spell and swapping between the pair!
I never played the original Inazuma release because at the time I wasn't into OCs then and if I passed this due to something as petty as that, I'd be missing out a heck of a fun time. Give them a shot!! There's a lot to experience and again, they're great even for a quick single stage or two. (I am curious about their lore too... It seems very cool!)
Merry Christmas and congrats on the release!!