I think that 10 will prove itself much faster when all the bugs are ironed out. I am squandering time establishing wether issues I am having are because I don't know about a new setting or whether there is a bug. That takes up a lot of time. So far about 70/30 bugs vs settings. I have spent much more time in that process than in the transition between 8 & 9. That seems logical considering how much more has changed. But I have spent hours (adding up to days) dealing with work arounds for buggy behavior.
And check out my thread
http://archicad-talk.graphisoft.com/viewtopic.php?t=11712
I am working on an old project in 9 today and there is absolutely no hesitation in any 2d process there. In 10 there is at least a one to two second hesitation between clicking and dragging. Sometimes much more. Absolutely no hesitation in 9 between the click and drag. Same on all my machines (4) but more pronounced the bigger the monitor. Makes me crazy as I move pretty fast and find myself waiting for 10 to catch up.
So for me in some respects (2d navigation) 10 is a bit buggy and definitely slower at present. (If any of you have any ideas on how to eliminate my 2d lag visit my post as I have tried everything short of re-installing system software)
As far as layouts and project information and smart linking of details, 10 is hands down the more productive (turn off auto update). I don't miss plotmaker in any way.
Ditto for design work in the 3d window. A few bugs but in general feels like progress.
But there are bugs in all areas of this release and they do lessen my enthusiasm for 10 somewhat. The combined process of learning new settings and pinpointing bugs has made me less productive on my first couple jobs but hopefully the bugs will get ironed out and my workarounds sufficient to make the going easier.