Last week I picked up a 55EX645 to replace the KF E42A10. I was concerned that in going from a 42 to 55 the TV would be too large for the room but the frame is so much narrower than the 42 that the increase in total dimensions does not make the set too overwhelming.
I do not nitpick about black levels, uniformity etc. I just look at the picture quality and I am very impressed. Out of the box I found most of the picture settings (scenes) to be rather garish with overly saturated colours so I used Cinema mode but then I found suggested calibration settings for an EX640 courtesy of :
Picture Mode: Cinema
Color Temp: Warm 2
Everything else: Off
Or at CNET
Home menu>Settings>Picture & Display
--Picture Adjustments menu--
Picture Mode: Custom
Color Temperature: Warm 2
Noise Reduction: Off
MPEG Noise Reduction: Off
CineMotion: Auto 1
-Advanced Settings submenu-
Adv. Contrast Enhancer: Off
Black Corrector: Off
Clear White: Off
Live Color: Off
LED Motion Mode: Off
White Balance: [see below]
-White Balance submenu-
Wide Mode: Full
Auto Wide: Off
4:3 Default: Off [grayed out]
Auto Display Area: Off
Display Area: Full Pixel
Horizontal Center: 0 [grayed out]
Vertical Center: 0 [grayed out]
--Scene Select menu--
Power Saving: Off
Either of these give me what I think is an excellent picture.
In terms of other features the set easily logged into my home wifi network and connection to Netflix (once you enter your account info) is a one remote button simple process. We will enjoy this. The remote is small with lots of buttons and I do find that if I am not careful I do press the wrong one quite often.
The SEN (sony entertainment network) has a bunch of apps that do not interest me at all : NHL, YOutube, Crackle, NPR , Wiggles... which at first glance just look like links to web sites but I have not bothered with them. You can also rent or movies from SEN which is another feature I will not use. There is also an Internet Browser and an connection option that gives Yahoo TV with connection to news, weather , Flickr... Another option I will not likely use.
What has impressed me is the DLNA capability. I can put movie, music or photo files onto a USB key or external USB hard drive and play them on the TV. The EX645 plays a wide range of files including mkv files which have always been a problem for my 1st gen Apple TV. In fact with this and the easy Netflix capability I may not use the Apple TV very much at all and previously I was using it on a daily basis. I should add that the interface for this option is not very good. Often it does not show thumbnails or it shows files that are otherwise invisible - but it plays mkvs which for me is a big deal. Alternatively I can stream these files from my Mac to the TV using Eyeconnect or PS3 MEdia Server. Having an external hard drive is much faster than streaming. No more having to convert mkv files to m4v or mp4 - a great time saver.
I use my son's PS3 to play blu ray discs and they look stunning. I can also use PS3 Media Server to stream or copy movie, music or photo files from my comp to the PS3.
Sound from the built in speakers is no better than OK. There are optical and a single mini jack for audio out to external audio equipment - I use an NAD/Mission stereo system which sounds very good. I tried the Sony HTCT260 soundbar but was underwhelmed. It has various options for sound modes and a wireless subwoofer but the general quality of the audio is not as good as my stereo.
So, all in all I am very happy with the set. To my eyes and tastes it is easy to get an excellent picture, good sound and is very flexible in what devices can be connected and what file types it will play.
Edit: I played around with the settings on the Soundbar and was able to get acceptable sound from it when the correct sound mode is selected. If you can get this device on special it will be an improvement over the built in speakers.