Not very good really due to high price and cheap suspension. I certainly won't be getting one. The only real fault I have about the FZ6 is the soft front end which the FZ8 fails to improve on.
Yamaha FZ8 (2010-current) - Yamaha Motorcycle Reviews
World first ride - Yamaha FZ8 and FZ8 Fazer: Plenty of mid-range grunt with a surging top end - | Motorcycle News | New Motorbikes | Buyers Guides | MCN
MCN are doing an article on the FZ8 tomorrow, I'm sure it will all be pure speculation but will be worth a read.
New MCN February 3: Foggy's secret bikes - | Motorcycle News | Bike News | Motorbike Videos | MCN
http://www.motorcyclenews.com/MCN/News/newsresults/New-bikes/2010/january/jan2710-yamaha-fz8-official-image/
Looks much better than the monochrome images.