Been using this frame exclusively since she came out. Don't know what the complaints are (maybe people are bad at building her?), but my only complaints are QoL. This review is fresh off doing multiple 30 minute arbitrations and one 60 minute arbitration.
Anyway, Balefire. Balefire deals a ton of damage. I was one-shotting level 120 arbitration enemies with a sub-optimal build, with uncharged shots. Keeping up with an Ash, and even outpacing him when the drones were being less rude. And now that I have blind rage on my hands, it's about to get crazy. My only complaint about this weapon is that the charge animation, while cool, slows you down a lot and triggers far too easily. IMO, the animation should only kick in at half charge, as that's where it starts dealing significantly more damage than uncharged shots. Also, since shots take so long to charge, maybe increase the damage on them a bit? For the sacrifices you need to charge Balefire for, you can just deal more damage and have more mobility by just using uncharged shots.
Shield Pillage. What a fantastic ability. So far, unless I haven't payed attention, I haven't died. At all. This makes Hildryn at higher levels very powerful, yet very engaging. I love it, I love it I love it I love it. I can not give this ability more praise. Though, it should honestly take in shields from 10% of enemy health at base. Seeing a squad with a ton of Corrosive Projection makes me wish I were using Rakta Dark Dagger.
Haven. Hildryn's only actually useless ability. I want to like this ability, I really do. And it's good on paper. But fact of the matter is, this ability drains far too many shields and deals almost no damage at all in high level content. Please just axe the entire "damaging enemies" part.
Aegis Storm. Aegis Storm is supreme fun, and with the bug fixes it's actually useful. It's a good "I NEED CC RIGHT NOW" button. Only thing I can ask for is, yet more QoL. This ability should not have a channel cost. Instead, increase the per enemy cost by like 5-15 shields per second and we good. It'll drain more when you're surrounded, but you'll be able to fly around at your heart's whim. And fun is what Warframe is about, right? Also, please change the camera position and allow us to zoom.
All in all? Hildryn is my favorite warframe yet. This veteran of four years has finally got something they wanted in this game. An active bullet sponge who can dish it out while taking it.