Two reasons:

1- Because it's precursor the Panasonic GH-1 / GH-2 DLSRs do not use line-skipping to reduce resolution. ( they down res via pixel binning )

2- Every camera that I've ever heard of that uses line-skipping to down res always has aliasing and moire issues, and it's been confirmed by many shooters that the AF-100 has no visible aliasing or moire, even when shooting highly detailed environments with wide angle lenses.

My understanding is that the current crop of Canon DSLR cameras all have OLPF, but because these filters are designed for full resolution from the sensor, they do not prevent aliasing or moire when shooting at much lower HD video resolutions. ( i.e. 1080P, 720P, etc... )

Pixel binning (as I'm sure you're aware) is combining adjacent pixels to form a single effective pixel. But used with a Bayer array, the problem is that adjacent pixels are filtered to different colours, which makes pixel binning far more problematic. In this case, and doing it in real time, my suspicion would be that it will be too coarse an effect.
But up until now, every camera that has used pixel skipping to down res has not had an OLPF matched to HD video. If the AF100 has no visible aliasing or moire, it's an indication of the presence of a suitable OLPF - not necessarily that it's not pixel skipping.

An OLPF in a DSLR suitable for stills will be of no use in preventing video moire/aliasing - if it cut off at a low enough frequency, the video would be fine - but the stills would be unacceptably soft! (So don't expect the AF100 to ever give stills a fraction as good as a GH-1, even if it were to have the same sensor.) You can't have your cake and eat it.

Practically, when comparing it to such as an EX1, the differences are far less about quality as usability. The AF100 (and Sonys F3) will give far shallower depth of field - but will have significant disadvantages as a "general purpose" camera, most notably in the effective absence of a cost effective servo zoom lens of decent zoom range, manual operation and aperture.

My preferred way of filming till now has been an EX1 for mid and wide shots using a letus adapter with 35mm still camera lenses for closeups and some mids and using the 10 bit out with a Ki Pro.

The panasonic seemed at first to offer a good solution but now with possible line skipping the use of four third lens and the expense of decent lenses for the format. The 8 bit out. The crop factor issues and Super 16mm lenses not covering the sensor, combined with a lack of information leaves me AMAZINGLY wondering if the EX1 is still the best deal for quality flexibility and cost effectiveness.

I agree with Mark that the EX1/3's are an incredible value, and I have no intention in selling mine in the next few years. I use the NanoFlash on them, I know that the NF is only 8 bit. But I am not sure the EXcams at 10 bit really are justified, the signal is not 950 quality. The NF 422 at 100mb/s is really amazing looking even after some heavy grading.

What I think is really cool about the AF100 is the SDOF properties in a compact inexpensive camera. And as an added plus I can use my old FD and FL lenses and all my newer L glass. And some new exciting glass like the Voightlander 25mm f.95. And others will be able to use their cine quality glass and Nikon glass.

This is not an ENG cam it is really a great 7D class solution. A real video camera. I am still keeping my 5DmkII as well it is also a great tool.

So for me it is my new SDOF adapter that will be easy to use and light.

Stills with the AF-100 are at HD video resolution only, thus at 1080P they are roughly equivalent to a 2 Mpx still camera. Also this camera can't do the quick punch-in for focus, which makes me think that the 1080P optimized OLPF might be the reason why.

The EX-1/3 cameras can resolve 1000 lines, which make them one of the sharper 1080P cameras on the market. The AF-100 resolves in the same range, though the images are supposed to have a more "organic" look to them. Hopefully we will have some direct side-by-side comparisons in January, to see how these new cameras hold up.

Shallow DOF is the main reason for buying these cameras, and I doubt that servo-zooms will ever make these cameras suitable for ENG work. The lens alone would just be too big, too heavy, and too expensive.

Myself, I'm keeping my Panasonic HMC-150 for ENG style work. ( one small bonus is that these cameras share the same batteries )

Yes it is.

Or it could be, depending on whether or not they used the multi-aspect sensor as they have in the GH1 & GH2.

But at any given aspect ratio, it crops to a section of the chip which has the sama area as a 4/3rds chip natively designed for that particular aspect ratio. Each aspect still adheres to the 4/3rds standard which is a 21.6mm diagonal imaging area.

Software has an easy time piecing together an image from a fixed chart. But I wonder about real world resolution. Both compression and noise reduction can reduce real resolution. Subjectively the AF100 images don't look particularly hi res to me. But perhaps the files are just not sharpened to my preference.

Of course I want the perfect camera for $5000, and that's not going to happen.

According to the brochure then a cropped 16/9 frame from the 17.3mm x 13mm sensor which means I will be able to use my 16mm superspeeds and if I use an aspect ratio of 2.35 Maybe a little bit of vignetting and maybe a little bit of zooming in on the frame with the 12mm but all in all with a nanoflash or ki pro this should be outstanding.

One thing I noticed is that the pics in the brochure seem to be lower in quality than my Sony EX1? Softer?

I would read too much into an on-line pdf, chances are it's not a full print quality resolution.

Panasonic claim the frame size is almost the same as movie 35mm and could be if it was just under 22mm on the diagonal for 16.9 But ti isn't The brochure states it's cropped and so therefore is less than halfway between 16mm and Super 35mm film Unless I'm missing something.

Super 16mm aspect ratio 16.9 Frame size 12.52 by 07.41 mm
Four thirds aspect ratio 4.3 Frame size 17.30 by 13.00 mm
Movie Super 35mm aspect ration 2.35 Frame size 24.00 by 12.97mm

However this is a fantastic size for me!

The brochure that's making the rounds on the web looks like a low-resolution PDF which trashes the quality of the images. ( also some of the images in the brochure are recycled from other Panasonic brouchures that are quite old now )

This still looks like a mock-up of the final brochure to me.

I've seen these measurements (17.3mm x 13mm) on brochures and official Panasonic websites for the GH1 as well, despite the fact it uses the larger multi-aspect sensor. I think these are just the default specs that they write for all their micro 4/3rds products.

The important thing here is to look at the aspect of the AF100, which is 16:9 native. It is probably derived from a 4:3 chip and my best guess going on the footage I've seen, is it's a very similar sensor to the GH1 ( if not the same ). So the actual size will be a lot closer to S35, than to S16.

If you're planning on shooting 2.35 with lenses that will cover S16, you might still have problems with vignetting, as has already been pointed out. I guess you could always look through some of the image galleries on Flickr or similar, where there are many samples from people shooting m4/3 cams with c mount lenses. Of course, a lot of these old 16 lenses wouldn't cover S16, but it might give you more of a feel for how it would work.

Oh dear uncertainty creeping in again.

My take is If we have to make a choice between what the brochure and Panasonic representatives have said IE the sensor is cropped from a 17.3 x 13mm frame and what others think but is the opposite. Really unless we hear otherwise and if we have been misinformed but we should accept what the brochure says.

For all of us though this is frustrating and unless someone who knows for sure speaks up then who can seriously buy a £4000 camera if they don't know what they're getting?

Mark, this link might be some help. It's one of the best explanations IMO, of how the over sized sensor in the GH1 works, especially in relation to other m4/3 cameras such as the G1.
The biggest Four Thirds sensor yet (Four Thirds User)

Obviously this doesn't help with S16 coverage, but I would imagine that you would be lucky to get full coverage at all focal lengths. I'm hoping to rent an AF100, sometime in the new year, when they are more widely available and this might help decide if it is worth the extra outlay over the GH1 for me.