I just bought an LG 55UF680T last weekend. It's a 55-inch 4K LED TV (non-3D), with full 4K playback capabilities. I got it at great price, and it's even cheaper than the 47" LED TV I bought 3 years ago.
Some thoughts:
- You need at least 50-55" to appreciate the video quality difference from 1080p. Anything smaller and the video quality improvement will be virtually imperceptible compared to a Full HD set.
- The video quality is incredible, IF YOU HAVE 4K CONTENT. I cannot stress that enough. If you only have 1080p or less (which is what everyone has at this point), then it will look soft and muddy. I tried a number of HD movies and TV series of varying bitrates, and they all look a bit worse now when viewed in a 4K TV. You have to understand that 4k has 4x the resolution of 1080p, so the TV will upscale the 1080p stream to fit into 4K, leading to smoothing of edges which will make it look less sharp. Think of it like viewing DVD's on a 1080p screen. So if it's like that with 1080p content, just imagine how bad your DVD's will look on a 4k TV.
- At the time of writing, there are close to no 4K content available, and no input sources yet. Most sources are still on 1080p. True 4K requires either DisplayPort/Thunderbolt inputs or HDMI 2.0 inputs to deliver 4K @ 60 hz. No 4K TV has DisplayPort and most input sources like BluRay players, laptops, NMT, PCs, Apple TV, PS4, or Xbox one only have HDMI 1.4 or lower. The only way you can output a 4K signal to a TV would be from a PC with a Graphics card like Nvidia 960 which has an HDMI 2.0 output, or get a new set top box like an Nvidia Shield TV. Right now, not many people have a graphics card like that, and the Nvidia Shield TV is not even locally available.
- I downloaded about a 4k demo clip of a little over 1 min of footage, which was around 250MB! Extrapolating that to a 2-hour length movie, that will be around 30GB! I don't know about you, but I don't have the space, bandwidth, or patience to download something that big for just 1 movie. It's just not practical. I'd rather buy a 4k BluRay player when it comes out.
In summary, I don't regret my purchase, since the price was still pretty affordable considering what you get, and you have a bit of a future-proof setup. That being said, I think I would have been completely happy with a 55" Full HD setup.
I think we've reached a saturation point with Full HD. I believe it will be quite a while before 4K becomes the norm. It will take at least another 5 years. I think it will only become the norm if they completely phase out the 1080p sets. Although the jump in video quality is close to DVD to HD, that is only evident in bigger sets from 50" and up. Very few households have space for that big a TV. Unlike before, we're talking about 27-32" CRTs, which were not that big, and so people wanted to have bigger screens. But now, few people would have space for anything bigger than a 47", and at these sizes, people would not see a distinct improvement of 4k over full HD.
So my advice is, especially if you have a ton of HD content, and you only have space for a TV 55" and below, to just stick with Full HD. Save your money or use the leftover to buy a good surround setup.
But that's just me. Cheers! :-)