I just got a 2012 42" E50. It had been on my short list for a while, and I was checking out HDTVs in the stores and online. I was going to take a wait-and-see approach, but Amazon was offering a $100 credit ($640+tax and free shipping) so I couldn't resist. I don't care that much about 3D--I like it at the movies, but don't care at home ... my budget has dominion.
Keep in mind I upgraded from a dirt-cheap Vizio Razor edge-lit 32" and the only comparisons I can make are to the Vizio, the HDTVs I checked out, and my brother's 55" Panasonic Plasma, which is a few years old.
Hardware: plenty of inputs for HDMI, USB, SD. The panel isn't the "thin bezel" of some other HDTVs I've looked at, but there's no gorilla glass and no glare.
Picture: the viewing angle is fantastic. This is good, since the stand doesn't swivel much at all (it's soon going on the wall). I'm familiar with IPS panels from graphics work, so I wasn't surprised. The default motion smoothing is "strong" and it makes everything look like "days of our lives." I turned it off, and then yesterday set it to "weak." It improves picture quality for HD broadcasts quite a bit without the soap effect.
Bleed: I could not detect ANY, and that alone made it worth the upgrade from older edge-lit LEDs. Blacks and darks were very good; significant clarity and detail over the Vizio. Not as good as a Plasma. I do think it's superior to my brother's plasma, which suffered some degradation after a while, but that could be a sibling thing. (He's a plasma man, and I'm an LED woman.)
I'm still futzing with calibration. The Viera offers a few different modes for owners who aren't as OCD. Picture settings aren't "universal" so it's possible to set up each HDMI device differently. I was able to get close to the "cinema quality" of my brother's older plasma. I like that it's possible to turn off or modify all the features (my Vizio was pretty much "you get what you get").
I tried out most of the other features to test them out. I have an Apple TV 3 so I can easily send all my content from my Mac to the TV, and for streaming Netflix, so I don't care much about the apps. I didn't have a wireless adapter so I hooked up my ethernet cable. This was the only time the remote wasn't intuitive. It has an alpha-numeric panel, but for inputting network information you click twice and use the on-screen keyboard. (The onscreen keyboard was a lot easier to use than my LG BD player!)
Internet Apps: You can go into Viera's app center and there will be a PiP of whatever your watching on TV in the menu. Netflix streaming worked well, Hulu+ didn't .... lots of lag. (This is a chronic complaint for Hulu and not unique to the E50, but I want to find out why.) I could not locate some of the apps mentioned on Panasonic's web site, so I'll find out if I can add them. It allows Skype (with a webcam) and some social networking apps. The Netflix navigation menu is a bit easier than the Apple TV, though there was more buffer lag at the beginning. There are more apps I didn't check out, and plenty of room on the scrolling menus for several more.
There's enough to replace a Roku or an Apple TV if you were using these devices just for internet streaming content.
Remote App: I have an iPad and tried out the Remote App, but not extensively. I can confirm that it works, but not how well it works. If there's interest, I'll try it out further.
DLNA: Didn't try it. I bought the AT3 because DLNA on OSX is flaky. I could try it out with my OSX PS3 medialink software if that's something people want. My experience is that both USB and DLNA playback will always be a bit limited in terms of accepted formats.
Remote: overburdened to excess like all of them, but not counterintuitive.
Gaming: I'm not a gamer, but the few reviews on the TV from gamers have been very positive.
CONS: there doesn't seem to be a default setting for Cable TV or devices. When you turn on the TV, it remains switched to whatever you were using before. That is, unless I haven't figured out something yet. I want to have cable set as the default.
Sound: Um, it sounds better than the Vizio.
The wireless adapter is a separate purchase. Only the ET5 and up have it built-in. A cheap move by Panasonic.
Overall assessment: There's a lot of features in that "something for everyone" way. For example, It's possible to hook up my Lumix camera and control it with the remote, but .... why? Swiping through the Remote App for the remote controls (on a few different pages) seems absurd when the remote is right next to me. Of course, if your SO hides the remote, or the dog eats it, you have a backup.
For what I paid for it, and for my small studio apartment , it's fantastic. If you are moving from an older LCD HDTV, and want to lose a media box (or not buy one), it's an even better deal. At the normal high retail price, well.... if you factor built-in wifi (the adapter is $70) and think you might want to play 3D content at some point in the future, it's worth checking out the ET5.