3D I also did not know before and I have therefore directly bought the 3D Blu Ray "ice queen" for my children and "Avatar" for the parents and tested. I am extremely impressed. Sharp picture, no clouding. And the 3D effect is pretty wicked good.
The sound can be described for a LED TV also very good, but I did not use because I NB3530A 2.1 Soundbar with wireless subwoofer connected the LG. The nice thing thereto, which recognizes the Magic Control remote from the new TV the connected LG Soundbar directly and I can control the volume using the LG Magic Control. Pleasant.
I am so far noticed nothing negative. I am excited about this 4K TV. The TV is also future-proof, as it already has 3x HDMI 2.0 inputs for future 4K TV / 4K Blu Ray.
I highly recommend this monster of TV each. I bought him at Otto. Because this TV is favorable offer.