I visited a Tiger Direct store near by which had the $1300 Seiki 4K TV set up and hooked up to a gaming PC. I didn't know what to expect as I've heard good and bad things about it.
http://www.tigerdirect.ca/applications/SearchTools/item-details.asp?EdpNo=7674736
Hour long unboxing and testing: http://www.youtube.com/watch?v=uXBu9nxLN78
After about 20 minutes of playing around with it at TigerDirect and testing certain things, below are my impressions:
1. It handles the following resolutions:
4K@30hz
1440p@75hz
1080p@120hz
4K@30 is perfectly fine for productivity and desktop but gaming isn't ideal at 30hz. Its still doable, infact I didn't mind it much, but I do notice a slight visual and input lag. 1080p@120hz input is amazing and this alone is worth this TVs purchase.
2. Picture quality
As a TV, the picture is decent but not great. You can buy a 1080p TV for this price form Samsung or Panasonic that will demolish the picture quality that this TV offers.
In terms of a computer monitor however, the picture qiality is excellent and you would have to buy a very high end IPS display to match it.
3. 1080p to 4K scaler
Vor video sources - not bad. video looks slightly sharper with little visible artifacts.
For PC and desktop - absolutely terrible. I am not sure if there is a way to turn off the scaling features when using PC mode and if there is, it would be an absolute must.
Conclusion
Based on what you are looking to do, I would rate this TV in the following manner
Good Buy:
As a PC gaming TV (1080p@120 hz) this TV is awesome. As good as those 120hz monitors but with an IPS pannel that delivers a much better picture.
As a desktop and productivity monitor, the TV is big enough to be used at 4K resolution and 4K @30hz isn't an issue
Don't buy:
As a TV with little to no 4K content, this TV isn't a great purchase. Spending the same money on a 1080p set will deliver a better picture.
Gaming at 4K@30 hz is a no go
