David Spark on iWork for iCloud:
While the experiment ultimately worked and he could see what I was typing, it was hardly simultaneous. Basically, we discussed and I wrote and he waited for the changes to show up, which happened about 30 seconds after I typed. If he typed anything on his side (even just a space bar), I got a conflict message on my end and had to pick a version to become gospel. While I think Apple is nailing the “productivity app in a web browser” part, they still have work their work cut out for them on the collaboration part.
I’ve had a different experience. I use iCloud Pages to collaborate with a writing team and iCloud’s performs marvelously for us with three simultaneous editors.