wow, crazy to read posts here about people complaining it's not a sufficient enough upgrade, or too expensive, not worth it, etc. i mean really?
first of all, with its new compression abilities alone, importing into an avid (what i use) will be a vast improvement over the mark II. to complain that it doesn't have a 1080p 60 chip - which the 1dx doesn't have either - therefore, it's not worth it, is just plain silly. first of all, shooting high speed is so yesteryear. i don't know many DPs, producers shooting 60p in the broadcast world i traverse in anymore - which is high-end sports docs. maybe if you are making vimeo videos, having a 1080p, 60 chip will rock your musical montages... right there with all of them TL videos, which are yesteryear as well. if you want to make slow mo video step up to the phantom and do real slo mo.
what matters the most and why we use these cameras are to tell stories. for example, having the ability to shoot without a ton of lights adds to the versatility of the 5d and allowing more intimate access with the subject. now you have an upgrade coming out that will allow you to shoot in even lower light conditions, while improving picture quality -- wow, that's a filmmaker/tv maker's dream come true.
since somebody here mentioned c300, let me chime in: the c300 was not built from a 5d. in fact, it was three years in the making (do math) and was based on canon's video cameras - not DSLRs and targeting cinema DPs, NOT 5d users. the c300, is most amazing with capturing images in low light - just breathtaking. however, it's nowhere close to 5d mark II and mark III with regards to versatility and ease of use, especially, in a run and gun world.
and really, does anyone care what vincent has to say? obviously, canon doesn't.
lastly, i edit and shoot extensively with the 5d in the high-end world of broadcast TV. we also use a lot of footage from RED, sony F3, Alexa and Varicam. the 5d mark II holds up mighty fine against all of those other, MORE expensive cameras. in fact, when all of the mentioned camera's files are transcoded into avid media composer with its DNX compression - real world for most of TV that airs - the mark II looks just amazing and hard to imagine that it's so much cheaper than those other cameras... hence that revolution it started. now canon is coming out with a new version that actually improves compression and greatly improves the video, offering better low light sensitivity to noise ratio - and that's not worth a grand more?
well, good thing they put a headphone jack in it.