I bought the Vizio 55 inch 552 before it came out a couple of years ago through their VIP program. Thought I got a great deal at the time, as they included a sound bar and blue ray player, with a cutting edge Smart LED TV for some feedback on usage, apps, etc.
Overall, I'm fairly disappointed with the experience because of a specific spot issue but am considering giving them another try.
For perspective, I'd rate myself as a moderate video purist - I've never gone overboard on calibration using whatever I could scrounge on the boards and playing with that, but I do go crazy at times over spots, pixels, etc.
The Vizio has had fairly good to great picture quality expect for one issue although many Samsung models I have seen have looked at least modestly better.
Built in WiFi has worked perfectly but Vizio and the Yahoo TV Widget engine have been a little disappointing. My family uses Netflix extensively and that has worked very well although at times it has reset and had passwords dropped. They have not upgraded these apps to the extent I would like, but at the end of the day, the primary apps I need like Hulu, Pandora, Netflix, Amazon were there and any others I have tried have quickly been disgarded as unnecessary. But overall, I'd rate the apps as useful and effective but again below what I have seen in variety and quality from others like Samsung. More importantly, a recent forced Vizio firmware upgrade seems to have caused lots of problems across the VIA Vizio line, making some TVs useless due to resets. Mine has suffered as well but only to the extent of shutting off and rebooting about once or twice a week which is annoying but Vizio has not acknowledged.
Sound as others have mentioned has always been fine for normal family usage. With young kids, they never really feel the need for surround sound or even the sound bar, and the basic speakers on the unit work fine for normal usage.
I have had a specific issue with my unit, of a few small black discolored, blotchy areas about 2in by 1in. It is so faint, most people can't even see if or be bothered by it, but it has always bothered me when I notice it against a white background. Multiple efforts with Vizio support, sending pictures, etc., didn't validate the problem enough for them to offer recourse, and I eventually gave up and swore off ever buying another Vizio again. I just wasn't sure that the cost savings that Vizio offer were worth the tradeoff. I'm in the market now for a 60 or 70 inch and have been eyeing the Sharp models at Costco when this caught my eye.
With this relatively poor Vizio experience in hand, I'm not sure what to do and thankfully have until early next year when some renovations will be done to pull the trigger. In my mind, if you go through these forums enough, you will find someone complaining about every singe model out there - whether its banding, clouding, etc. I just am not sure with these larger TVs that they have nailed it down perfectly quite yet particularly with respect to uniform quality.
So if these TVs come out at these price points, I'd compare them to the Sharp 6400 series now at Costco which probably has a comparable price and no 3D. I'd say the comparable Samsung Smart TV models are at about a 25+% premium in price. I don't think that premium is worth it. So I plan on watching the reviews as they come in here and then potentially giving Vizio another shot. Hope its not a get what you pay for situation.