I'm just talking about in general. I have 1080p TVs in my house but my dad has 4K TVs all throughout his house and I don't see the difference. But I noticed that shyt that is broadcast/streamed is lower quality than actual media from a disc or hard drive so that may also be why I don't see a discernable difference, or it could be my previously mentioned terrible eyesight.
dunno how old your dad is or better yet how tech savvy he is but I had to tinker around with my TV settings to achieve a desired effect...I was disappointed initially til I googled around and found the optimal settings for my specific TV(s)...optimizing my 4K projector was a real pain in the ass tho