That's NOT GOOD.
I didn't wait 3+ Years for Canon to go backwards in the Megapixel count. I own a 5D Mark II and was really interested in seeing a 30MP or more 5DMIII.
All that talk about lenses not being able to handle more than 18MP right now is tech talk with no really solid evidence to back it up. I'm using a 5DMII at 21MP and shooting Macros and Landscapes and all my L-Lenses seem to be holding up just fine. Perfectly fine.
If you don't want more than 18MP just set your 5D Mark II to a smaller RAW file.
I often have requests to do huge landscapes and wedding portaits, even the occassional product shot which can be no less than 21MP for my clients. In fact, most of my clients are use to going with guys using Medium Format. But I also work at *ony and our product shots, almost 100% of them are now shot on the 5D Mark II. And again for lenses that aren't able to handle more than 18MP of detail, these photos come out amazingly. I'm not talking about 10-20 product shots a week, *ONY has hundreds taken of upcoming products each month by industry pros using the 5DMII.
Bottom line is, I've always been annoyed by people screaming for lower megapixel and higher ISO. I'd demand BOTH instead of picking one. It can't be done? I dunno we'll see. Either way, extremely disappointed by an 18MP 5DMIII.