I purchased this TV two weeks ago from a local big box store for $699. All features worked flawlessly for the first week. I especially enjoyed the SmartCast streaming feature. However, last weekend the family wanted to stream a basketball game from ESPN (which worked remarkably well the day I bought the TV). After an hour of fumbling with the menu network settings, resetting it back to the factory defaults, firmware updates, troubleshooting my home network and restarting my modem and router, I realized the problem was with the TV. I had my TV connected via Ethernet to my router and the connection speed was very high. I began noticing the on-screen network icons were continually changing from Ethernet to WIFI. It was trying to negotiate between connecting to the WIFI and Ethernet, causing my connection speed to drop to the point where streaming was impossible. (When an Ethernet cable is connected properly to a TV, computer, etc., and has a strong signal, it should never switch over to WIFI). I followed all of the troubleshooting steps listed on the Vizio technical support web page and the advice others offered online. Nothing worked.
After reconfirming that my home network was stable (all other devices were connecting to the internet, network cable was intact, and able to connect my laptop using the same wall jack), I decided to call Vizio tech support. In summary, we went through all of the troubleshooting steps again over the phone and reached the same conclusion- the network card, on-board Ethernet port or motherboard were bad). Vizio agreed to replace my TV without any hassle! Excellent customer service department! I am hoping I got a bad apple and remain cautiously optimistic that the replacement model will work just fine. If not, I will post a follow up message.