Ok,but does it answer if the video player comes with hardware decoding,or post processing video, sharpening, and adjusting contrast/saturation?
And from half of the links I'm not able to make out if the software comes with the stock OS, or from another OS loaded on the pi!
The XBMC people are working on XBMC for the Pi, with that and openELEC you should get everything that XBMC provides in terms of controls.
However, if you're looking for an out-of-the-box, fully working and polished media player, you probably want to be looking at something like a boxee, AppleTV, Roku or cuBox. Yes, they are more expensive than the Pi, but:
a - they are available now, rather than October or later (apart from cuBox, which is on preorder but supposed to ship in April)
b - they come with case, power supply, remote control, cables and all required storage (for the Pi you'll need to separately source a case of some sort, PSU, keyboard, mouse, HDMI cable, SD card and probably a USB hub, and you'll need to pick and install the OS yourself)
c - they come with a more extensive set of video and audio codecs (due to licensing costs, the Pi comes with a very minimal set of hardware accelerated codecs. To fully understand what is currently available, see http://www.raspberrypi.org/archives/592
and read all the comments, the short version is "h.263, h.264 and nothing else").
If you understand the limitations of the Pi and don't mind working within them, then the Pi is probably a decent buy (when you can eventually get one). But you do need to understand the limitations to reduce the chances of tears before bedtime.