I have been facing the same question as you for the last few years.
Because of the Canon 5DII I was able to graduate from shooting stills for newspapers to also shooting video for TV news but the biggest problem with video from the 5DII is that the vision is just too flickery for broadcast video, even with FCP, compressor and every trick I have tried, it's only really ok for static shots and focus pulls. I find the Panny GH2 is much better.
To date I have stuck with DSLR's because of the 'one box' idea, thinking it's easier to shoots stills AND video in the one camera.
I went from knowing almost nothing about broadcast video at the beginning to getting educated on the differences between broadcast news video cameras like a Sony XDCam or Panasonic P2 versus a DSLR Video enabled camera like the Canons, Panasonic GH2 some Nikon's etc.
To answer your question, if your goal is to shoot short clips with an arty theme, family or travel videos then the 5DII may be ok.
I have listed below a list from my point of view the pros & cons of DSLR video versus a dedicated ENG video camera.
DSLR Pros Cinematic colour, amazing depth of field, small, cheap lenses, small and portable
DSLR Cons Crappy 25P which everyone seems to be ga ga over but looks rubbish on TV because it flickers
25P is useless for pans, zooms, anything with camera movement.
Yes I know SHane Hurlbut does amazing stuff but his post work is mega buck stuff.
Canon 25P looks rubbish compared to 25P on broadcast cameras or any TV or movie
Pathetic sound options, no audio monitoring or audio meters on the Canons
The Magic lantern firmware hack is a pain in the neck to use and NOT stable
The Panasonic GH2 has audio meters and the firmware hack is impressive but no audio
monitoring. (I really like theGH2)
Lousy in low light (compared to broadcast ENG) A Sony or or P2 has up to 45db gain
easily thrashing a DSLR video, even with a 1.8, 1.4, .95 lens.
No cinema lenses with decent zooms, no power zooms.
Pro Video Beautiful creamy 1080 50i, 50P, 25i, over cranking under cranking
Proper over the shoulder form factor
Massive 4.2.2 dynamic range, huge EVF's, cinematic colour
Incredible low light shooting, 45 db gain with super low noise
Sony claim you can shoot a portrait off the light from a mobile phone screen.
Proper sound, with meters, monitoring, XLR and wireless mic options
Proper ENG zooms, Pro image stabilisers, built in 2 x converters, power zooms
For instance you can get a Fujinion 18x zoom with AF & built in image stab & 2x con
Pro Video Zooms hold focus while you zoom, DSLR lenses don't.
Pro Video Cons Depth of field not as cinematic as DSLR, BUT still ok if you shoot wide open
Costly & Heavy
For me, for the work I do, I find I'm heavily leaning to buying a proper over the shoulder ENG camera and hers why, it's one box with everything on it, one all round lens, you can shoot daylight, low light using a small video light and the output is industry standard codecs and SDI embedded audio.
But I wont do anything until canon shows their hand with the new models, I want to try full frame 1080 50P before I throw $30K at an ENG camera.
If anyone wants to tell me off here or mention the holes in my argument please go ahead, but for me these are my thoughts based on what I use video for.
PS , I still LOVE the look through the 5DII, I really hope the update has 1080 50p, because with that you can interlace the output to 25i and still get the creamy smooth vision.
A full frame sensor DSLR with hi dynamic range that shot 108050p would be wonderful, I would even forgive the rubbish audio.
By the way the GH2 720 50p hacked to 32 mbps looks brilliant, and the 1080 50 is great too, and if you de-interlace it at double frame rate you get 50P.