>>212947311
I do 1080p and 4K.
The biggest thing to notice initially is that while some 1080p blu-rays look amazing, there is a variance. 4K, on the other hand, virtually always looks amazing. You can watch the 4K version with confidence, knowing that it's about as good as the film will ever look on home video. The format standard of a 4K scan of the film is itself a vote of confidence, but the higher data capacity of the disc is also a great help.
There are some examples where I was disappointed by the 4K not being an extreme upgrade from the blu-ray, like Arrow's 4K of Hellraiser, but even if 80% of the movie looks interchangeable between blu-ray and 4K, there is that 20% where the scenes benefit noticeably. Usually, it's dark scenes or scenes with a lot of texture (close-up shots of make-up, fabric, bricks on buildings, etc)
The second thing to notice is that, beyond the detail and clarity, the contrast and colors look incredible. One of the reasons the horror genre has gotten so much of the 4K treatment, even for niche movies, is that all the blood and special effects and lighting style of horror movies, all the creepy sets they use, is really showed off by the 4K/HDR format.
1080p is definitely great, but 4K is a welcome upgrade that, hopefully, will become less expensive in the future.
