Finally watched this one last week via 4K HDR Amazon stream with rental credits accrued.
I enjoyed it as a scifi-action flick. The action was well choreographed with an Asian martial arts style I liked. Yes, there could have been better pacing.
Recognize that both Ang Lee and Will Smith are controversial love 'em/hate 'em film personalities- whether due to personal business issues and/or artistic styles.
I see what Ang tried to do re: put the clone issue in the Real World, and I felt the emotional and physical issues were handled realistically- how would you fare against your ~30 year younger self in a battle of wits, physical ability? I took it as a cool geek thought experiment. Younger version more agile/flexible, but older version heavier/weight advantage in close fighting, experience, wisdom, less reactive.
Whatever your opinion of Smith, he does emote well with down to earth reactions, and is in great physical shape. Didn't think I'd try another film of his following After Earth, but gave this one a try.
The de-aged version looked spot on and real most of the time for me, only a few moments where the uncanny valley reared its head.
Don't know if they de-aged him directly or put his de-aged face on another stand in actor, but generally done well.
Image looked great on my NX7. I'd pick up the 4K disc on sale/bargain bin at my sight-unseen price of ~$5/disc (or ~$10 for a standard 2 disc 2K/4K set), of course even better for less.