I am another very happy owner of a 55 EX645.
The picture is so good that I almost refuse to watch non HD programming of any kind. Had it for 2 months now and there are a few things I would add to my earlier post.
First is that I am now used to using the remote and the small buttons are not a problem because they have small raised dots that make the remote easier to use.
Perhaps the only weakness is the narrow viewing angle. If I move a little off center horizontally or vertically there is a noticeable but not major decrease in contrast.
I have connected my camcorder ( a 720p model) to the TV and the movies look great. Watching a group of 40 grade 1 kids unintelligibly singing Mele Kalikimaka on a 55 inch HD TV brings tears to my eyes .
I can also connect my iPad2 to one of the HDMI ports and find this to be a good way to Skype.
The biggest problem I have is of my own making. I have a 1st Gen Apple TV and a PS3 connected. But I also use the two USB ports with a USB key and an external hard drive. Also, I can stream video from my Mac to the TV using PS3mediaserver. I can play video files from all of those devices( the Apple TV chokes on mkv files, the others do not) and it drives my wife crazy because she never knows where I put various files. Why do I do this? Just because I can and I love to experiment with options
Really for my wife's sanity, and therefore mine, I should rationalize all this.