So, I've had the (Euro) HDMI dock for a few weeks now (as well as the black leather sleeve, which is nice) but hadn't really gotten around to testing it. Primarily because I hadn't gotten around getting a mini-to-normal HDMI cable - yes the dock has a mini-HDMI output. The cable in question is commonly known as an HDMI "A<->C" cable with male ends on both sides.
Let's get the details you all know already out of the way. We're talking about the ECR-D980, more info here.
The dock itself comes packaged with nothing. No extra USB cable, no HDMI cable (or even converter plug), nothing. Keep in mind that these up the total cost of ownership for the dock quite a bit. I got the dock for about 29 euro, add about 20 euro total before you have a second SGT USB cable and a mini-to-normal HDMI cable. So that's 50 euro or about $70 US minimum cost at the time of writing, significantly more if you don't search a bit to find the cheapest deals. You don't strictly need the extra USB cable, but it becomes annoying in most setups if you don't have it - you'd be switching the cables location a lot.
The dock itself feels like a solid piece of equipment, much like the Tab itself. It features a 3.5mm audio out, mini-HDMI out, and 30-pin Samsung "PDMI" USB / power connector (the same connector on the Tab itself).
I started out testing at a friend two weeks ago, using his Sony soundsystem (several HDMI ins & outs) and his 42" high-end-4-years-ago Philips LCD. We were however completely unable to get it to work. Having no clue which component the problem was, we gave up after a bit. Note that his LCD doesn't do 1080p, but max 1080i (at time of purchase, even 1080i was rare). So I borrowed his cable, and today I tried it (with his A-C cable) in my home, on my Samsung 6-series 37" LCD that does do 1080p, without any special soundsystem. Note again that I used a converting cable, not an A-C converter plug. I know people have reported problems using those.
As soon as I plugged everything in, I immediately had display on my screen. We still don't know what the issue was at my friend's house, but keep in mind that it may be a requirement that the display device supports 1080p. The signal received by the TV was 1080p30. I think this is the maximum the device will do, as my TV does support both 1080p50 and 1080p60 as well (and I regularly use both those modes).
(1) First, the dock needs to be connected (via the USB cable) to a power, or HDMI will not work. I actually used an old HTC adapter instead of the Samsung one, that delivers 1a instead of 2a, and that worked fine. Connecting it to a computer USB port (0.5a) reportedly does not work, but I have not tested this myself (yet).
(2) Second, the Samsung USB cable you got with your Tab is really short, using an extender cable is almost certainly necessary for most situations.
(3) Third, the 3.5mm audio out does NOT work while HDMI is connected (reported by others, not tested myself)
(4) Last, the backlight will NEVER go off when connected over HDMI. Not even using the power button.
So, when you have it all connected, you will see one of two things: a really narrow output of your portrait screen, or a screen-filling output of your landscape screen. I advise everyone to put the device in landscape mode and enabling the orientation lock before connecting. Note that the HDMI dock is also a really handy standard for landscape mode!
When in the normal Android UI, you can clearly see the artifacts of upscaling. You'll see whatever happens on the Tab on the TV as well, scaled up (and not using a good resampler). The Android UI does NOT suddenly see a FullHD screen (as I expected, but some may be surprised).
However, some applications that go full-screen do see and use the FullHD resolution. I have not extensively tested this on many applications. For example, the YouTube app appears to see FullHD, but I can not be certain. The stock Samsung video player does see and use the FullHD resolution, as far as I can make out.
I have tested playback of the following videos, in the stock video player:
(1) Iron_Man_2-DivXPlusHD.mkv - 81mb, 2:30, CCV1 1920x800 23.98fps, AAC 48000Hz stereo, 4.4mbps
(2) Cowboys & Aliens - Trailer.mp4 - 174mb, 2:31, CCV1 1920x816 23.98fps, AAC 48000Hz stereo, 9.2mbps
(3) v.2009.s02e03.720p.hdtv.x264-ctu.mkv - 1118mb, 41:22, CCV1 1280x720 23.98fps, Dolby AC3 48000Hz 6ch, 3.6mbps
(4) the.mentalist.s03e12.720p.hdtv.x264-ctu.mkv - 1119mb, 41:48, CCV1 1280x720 23.98fps, Dolby AC3 48000Hz 6ch, 3.6mbps
These four videos all played fine, with audio and everything. V even had subtitles, and those worked well. However I must note that the button to disable subtitles is disabled while outputting to HDMI. Not sure what that is about. DTS is still on my to-test list, but I'll get around to that when we get the setup working on my friend's soundssystem, where I can also test whether or not the output is more than stereo or always downsampled to 2-channel.
The video output is pretty good, but not without buts.
(1) First, as stated before, the backlight on the Tab will not go off no matter what you do, and you will see one of the first frames of the video as a still on the Tab. You can however still use much of the videoplayer UI (which is suddenly slightly different: amongst other things options like brightness and scaling disappear), and that UI only appears on the Tab, NOT on the TV. Now if only I could control that UI, over Wi-Fi, with my SGS ... (might be possible through DLNA, btw, a nice test for the future)
(2) When you look closely at the image produced, you will see that the postprocessing is not quite up to par to the quality you get from CoreAVC or even ffmpeg on a laptop or HTPC or whatnot. The difference does really seem to be postprocessing though, not bad decoding or scaling.
(3) There is some shift in framespeed. Not traditional suttering you might see when the player cannot decode fast enough, though, the speed seems to be fine. I think this has to do with the fact that first the Tab has to scale 24fps to 30fps, which is probably done with some pulldown scheme, and then my TV has to scale that to 100hz, again with some pulldown scheme. I'm sure the videophiles amongst you will understand what I am talking about, even if the jargon is not correct. If you're not following, you are probably someone who wouldn't even notice it. Also note that I have all video-enhancing features on the TV itself turned off (as always). Enabling the 100hz motion interpolation mode makes the issue mostly disappear, but I really hate the "homevideo" effect you get when doing that. All in all, when watching a 40 minute show, you don't really notice it anymore after a few minutes, but if you're like me you know it's there and see it. If it were 1080p25 instead of 1080p30, the issue would probably not exist.
All in all, it does look good and works pretty well. Unfortunately, though most of these individual issues are small, together they are big enough to prevent this from being more than a casual playback device. It comes close, but not close enough to being a home-theater device. However, who knows maybe XBMC can be ported and we'll get past a number of these problems.
I won't make any claims as to whether the HDMI dock is worth the money or not. You know the price, and you have a bit of information here, and more in other reviews online. You have to decide for yourself it it's worth it. Hope this is helpful and/or interesting to someone.