If you have the cash, heck yeah!
Seriously, there's no real content, but it's coming. Everything that I've viewed on 4K displays had an amazing image. There was great added depth to the image. I'm more sold on 4K tech with front projectors. My last projector was a 4K lite model, so it wasn't true 4K spec. It was rather close, and I LOVED the image it produced.
The demos I had of Sony's true 4K spec projector was $14,000. I'm hoping to see them under $10,000 in the next year or two. I'm still in the planning phase for my basement so I have time
I'm planning to buy one to replace the 55" LED I have in my loft space, I'm just waiting for the larger sizes (65"+ models) to be priced under $5K Canadian. CES is in a week so hopefully I'll see something up my alley.