4k TVs for watching TV networks

I was thinking about large, 4k TVs which are meant to be used in living rooms and how most TV networks broadcast at around 720p and 1080i. This is a question mostly for people who have used such a large and high resolution TV. My question is, just how good does the image look at those 4k TVs considering that it has to be upscaled to such a higher resolution than the original, in order to fit in the screen. Does the image get too blurry and also what is the general viewing experience?

Thanks for the help!

It depends how close you are sitting, in general I feel the upscaled content still looks better. I have the Vizio 50" 4k. What I like is the very low latency for consoles and the 64 zone active LED backlight. That backlight makes the picture so much more lifelike. For the price I paid for the 4k Vizio ($700) It's not much more than a bigger brand 1080p with the same features so it was a no brainer to me.

Make sure it supports the newest HDCP or when 4k blu ray becomes a common thing it will not be able to play the content due to digital protection.

I really like my Vizo though, the picture is great, the Smart TV features actually work! YES they really do work! It also has a Plex app if you set up a Plex Media Server.

1080 upscaled looks great on 4k imo. i have a 55" samsung 4k tv. as for 720, i dont notice the difference that much (watching tv and playing xbox360). network tv quality has always been sub par on 1080 panels so they will continue to look sub par on the 4k panel. i do think it does look slightly better since the 4k panel has better dpi. if anything take a trip to the store and check it out yourself. alot of the generic demos are playing at 720 or 1080 for lack of 4k content.

Thanks a lot for your answer, as well as your warning about HDCP!