My thought on the leaks:
Positives - The images are RAZOR sharp, and for all non-effects footage, grain has been managed but not scrubbed. No excessive colour shifts.
Negatives (to me) - Colour temperature is a bit on the cool side. Whites are paper white. Saturation is a touch low, some shots are a hair bright (Hoth rebel hangar & Jabba’s palace in particular). In things like pre-2004 home video releases, original trailers, original promo shots, fan film scans ala 4K77, IB Tech prints, there’s a bit of yellowy warmth, moreso in SW than ESB and ROTJ. In the leaks, things like skin and off-white clothing have a drained look. It’s not clear what they’re using as colour references - they say “matched to Colour Separation Master”, but you’d only want to do that for base colour correction of the raw negative scan - there’s always additional colour timing past that. Things like an archived “answer print” and an IB Tech print would be good references.
It is possible the colour timing isn’t final, and the HDR -> SDR conversion may not be final either. We also don’t know the purpose of this project.
The effects shots are a mixed bag. Shots that never had high grain look great - reasonable saturation even. But the notorious shot of the speeder going into Mos Eisley has a stark, desaturated look. Another shot with this same processed look is the Cloud City hallway fight with the smoke haze.
;;;
On the whole, it looks technically the best it has ever looked, but currently is going more for a “shot yesterday” look than a classic look.
Sounds like they’re doing everything right (and then some) in the sound department, though.