well I don't know about 1080p, but I instantly noticed change for the good once I switched to HDMI on my 720p/1080i TV especially for the areas where color fades into black.
You pointed out one of the advantages of HDMI and that's a much broader and accurate color spectrum... that is if the source takes advantage of it. Not all "1080p" video is created equally. This is why some "1080p" movies and games don't look much if any different whether they are displayed in their native 1080p resolution or downscaled to 720p.
Considering 1080p has twice the resolution as 720p you'd think it would always look better, but so much has to do with the original source. I was just having a PM discussion with someone about 720p and 1080p TVs, and how explaining how the advantage of higher resolution displays is when viewing images that have a lot of fine detail.
For instance, if the display is just showing a single solid cover, obviously you wont see any difference what so ever between a 1920x1080, 1280x720, or for that matter a 1x1 display. Fortunately though, who wants to watch n image that is nothing but a single splash of color.
That said, there are a lot of games and movies that do not have a lot of fine detail, and instead have lots of screen area filled with large 'flat' images. In those cases, you really would be hard pressed to see an significant differences between 1080p and 720p.
Also some people make the mistake of comparing 720p video on a 720p display and a 1080p display and wonder why they don't see much if any difference. The problem here is that as advanced as video processors are today, they can't really create original detail that is not already in the source material. So while it is true that a 1080p display will scale 720p up to 1080p, it's going to still have the same amount of detail as shown on a 720p displays... only it's using twice as many pixels to show that detail.
Now when the source is native 1080p and has a lot of fine detail, like most movies, that have been well shot, preserved, and given a proper telecine transfer and/or digital processing, then you're definitely going to see a big difference between 1080p and 720p. The same goes for games that have been developed and programmed with lost of fine detail. The difference between a 1080p and a 720p game can be quite significant.
Another important advantage to HDMI over component, VGA, S-Video, and composite is that they can only carry analog signals, while HDMI and DVI carry digital signals. This is very important because any time a signal has to be converted from digital to analog and analog to digital it is going to inevitably pick up some conversion artifacts. While it's true converters are much better today then they have been in the past, none are perfect.
Having a digital output is a big advantage in this regard because these consoles are digital devices, creating digital data. Without HDMI, that data must be converted to analog, then it can be carried by the analog cable to the display, and if you are like most consumers who own these next-gen consoles, you most likely have a digital display
(Plasma, LCD, LCoS, DLP, etc), thus that analog signal will have to once again be converted back to digital. It's one thing to convert a signal once, but now you're having to do it twice.
Another advantage of HDMI is that it is less prone to signal interference.
HDMI also allows you to transmit multi-channel lossless audio as well as the new HD audio codecs, like Dolby TrueHD and DTS-HD.
One other advantage to HDMI is that unlike analog inputs, it is HDCP compliant. This means if your playing a video that has been tagged with the ICT
(Image Constraint Token), then you'll be able to see it in its native HD format. If your using an analog input or even DVI without HDCP, then the ICT will force your TV to scale the HD source down to 1/4 HD
(540p). Currently, as far as I know, no one has ever used the ICT option to date, so currently it isnt an issue, and I doubt ICT will be used regularly until piracy of HD material becomes cost effective on a mass scale. But this could change at any time.
Any way, these are all some of the advantages of HDMI.
Now to add to the confusion, there are also differences between the different versions of HDMI. MS deservedly or not, got a lot of criticism for not using HDMI 1.3 for their Elite model. I suspect they will be switching over to HDMI 1.3 in the very near future... but for those with 1.2 there is no "upgrade" option.
