FF is sent from a good place to all us lovers of wideangle photography!
The speed is ok (compared to a 20D) except a bit slow to see the image being displayed on the LCD monitor after the shot. I've never filled the buffer of 10 RAW-files yet.
Great viewfinder, excellent professional body, 45 selectable AF-points(I use them all, manually!), 3fps and so on. Did I say 11 Mpix Full Frame sensor..? Cool.
The files you can get from this camera is awesome. Very filmlike AND high resolution. The 20D, for example, have lower noice at higher ISO but the images don't have the same "feeling". My solution to the max ISO of 1250 is to get faster lenses, primes.
But you need to really work for the maximum quality. This ain't no point and shoot. Motion blur i.e. is more visible due to the high resolution. And you need good lenses to keep the sensor well fed.
On the negative side: Some times it can be heavy to carry.
A dark screen, hard to see the blue histogram against black background in sunlight. (Why a dark blue histogram?) No longer can I rely on the histo and screen (takes to long time). I have to become better at exposures from the begining (always using manual mode and spot metering).
I choose between a used 1Ds and a new 1DmkII and I'm glad for my choice. (Using it for studio, editorial and street etc.)