I can't say I know much about the camera, but just looking at it's specs - it can shoot in RAW, has hot shoe mount, 12mp, and a Micro Four Thirds sensor so it sounds promising.  You would have to shoot at ISO 100 with perfect exposure though to avoid noise.  You are still shooting on an slight smaller sensor than the APS-C sensor cameras (Canon 50D for example) but much larger than a point and shoot.

DpReview certainly goes in depth though
http://www.dpreview.com/reviews/OlympusEP1/

They were quite positive about it's quality

Arguments will continue to rage about the E-P1's features and performance but few could find any serious fault with its image quality, which is easily as good as most SLRs at a similar price point. Yes, it's fractionally noisier than the best APS-C models (particularly if you turn the noise filter off to get the maximum detail), and yes, the dynamic range isn't as good as the very best-in-class cameras, but honestly we're splitting hairs here. Our overall impression of the E-P1's image quality was and remains overwhelmingly positive.

I shoot with an E30 which has basically the same sensor - actually the EP1's is a little newer and has some improvements.

In terms of image quality, as long as you get the focus right (which will be comparatively slow) it will be on par with something like a Canon D90 or Nikon 50D - the actual IQ depends on which lenses you use. If you use it with something like the existing 4/3 50mm macro, you should be very happy with the results. I hear the kit lenses are on par with what you'll get in an APS-C kit lens, not bad, but not great.

Thank you all, that helped a lot!

I think i will give it a try.

I also looked at the panasonic gf1 but at the moment i think the e-p1 will be my choice.
i think i can live with a slower af for better lens comparability, in body is and higher dynamic range.

I like the camera with the pancake lens but with the zoom it doesn't seem much smaller than some of the small dslr's and it is handicapped by not having a viewfinder.  Olympus are bringing out the E-P2 in January and I can see the price of the E-P1 crashing, if you can wait that long.  The E-P2 will have an electronic viewfinder add on that I would definitely want if I was going to get one of these.  Using compact cameras with no viewfinder, there are times when I wish I had my dslr.
http://www.dpreview.com/news/0911/09110501olympusep2.asp

I have this camera, bought as a easy to carry, lightweight travel / landscape camera, alternative to my 5D. At base iso (200) this camera's images (as far as noise is concerned) is as good as my 5D. I've used it in the studio, hooked up my strobes to it and it works like a charm. There is no reason why this camera's images shouldn't be accepted for stock. Two points. Do not use a smaller aperture (larger number) than f8. Seriously, diffraction kicks in big time and you'll see less sharp images at f 11 and especially at f16. But remember, because this is a small sensor, f8 on this camera is about the same as f16 is on a full frame. Second point, the focus is slow, and so it's not well suited for capturing any kind of movement. Yes you can pre-focus and snap the shot when the action meets the pre-focused area, but the manual focus is not great and the focus points are large so it can focus on the wrong area easily. The camera, imo, is best suited for travel, landscapes, architecture, and more or less posed portraits. I do love the camera, it's light weight, small, and takes great photos, but it has some serious limitations. There are cheaper options for a stock camera that will produce equally or more viable stock images. I think this is not a good option for a first stock viable camera, it's good as a second, carry along travel camera.

thank you all for that great informations!

there are some more things i consider ;-)

i think i will buy this great little camera next week.

i don�t think i will buy the e-p2 as i don�t want to pay that mach for thoose (to me rather small) changes. I didn�t find much info which things really changed from e-p1 to e-p2, but i think the sensor is the same. i don�t need the viewfinder and i don�t care if the af is slightly faster (and has af-c).

for focusing speed i would like to know if soemone figured out if there is a way to use the 17mm lens with hyperfocal distance?
i know this won�t be easy because one would have to gauge the distance and then manually focus on that point.
i could shoot from the hip like in good old times with my lc-a 
does anybody use leica lenses in hyperfocal distance and is it working well?

thanky you, alex

Have a look on the micro4/3 forum on DPreview - sign up there if you haven't already, there's lots of EP-1 users there, many of which have quite a lot of experience and can be very helpful.