The filters above your inventory also filter the storage, which helps. Only seeing 3-4 things at a time is much less convenient than the 10 in Flash.
You also have much less storage overall. Especially in the apartment. 30 slots total for everything is a big downgrade from 30 each for Wardrobe, Equipment, Consumables, Valuables and Toys. Not that I ended up needing 30 slots for Valuables and Toys.
I also hope they overhaul it in the future. Or let us buy extra storage. Money sink?
They really needed to get feedback on the UI before committing, didn't they?