a)  ...quick transistion....? --> for me Yes. For the office, No. Most people are reluctant to make the effort to learn. What was anticipated to be a 1 year switch is on year 3 now. Interestingly though, all (in the office) who have made the switch say they would not want to go back to autocad.

a)  Has it been a quick transition or more slow?  Just using Revit on the projects that demand it; that part went quickly once engaged.  Otherwise, we are trying to save overhead expense (learning curve, licenses) at this time of economic recovery. We are keeping a couple of us active in revit, but if there were no active projects in Revit, we wouldn't be trying to transition at all right now.  We have a strategy in place for bringing other team members into the fold, but we will primarily lean on the ones that know it already.   Has there been any push back or has management taken a top down approach to pushing the use of Revit? Once again, we knew the Great Day of Revit was coming; it couldn't come at a worse time when many businesses (and clients) in our area of the U.S. are still recovering.   We don't want to absorb the full cost of transitioning in one fell swoop. 

b)  What do you see as the biggest challenges with Revit use? In AutoCAD & ACA, one could get by without knowing the full breadth of the program.  A basics-only user could fall back on the "old way" in CAD and get some good results on paper (albeit not as effiiciently).  Revit requires full product knowledge and in my opinion is eliminated the dabbling that non-drafting PMs sometimes need to do.   What are the benefits in your opinion? What you see is what you get.  You can cut a section anywhere and figure out details and coordination issues in a flash.  Not necessarily a Revit specific benefit, but a BIM benefit, I guess.  Specific to Revit, many of the concepts with regard to user interface and general functionality (project browser, etc) are familiar to ACA users, even if they aren't exact.  That helps the transition for us.

c)  What is your favorite thing about using Revit?    Everything updates throughout model.  Worst? Everything updates throughout model.  Instead of tracking down constructibility issues and conflicts from sheet to sheet, my project review is mostly spent making sure annotation isn't showing up where it's not supposed to and vice versa.  It's quicker to fix the latter but still--a different kind of follow through is needed now.  A sheet that was perfect before is no longer perfect even though I didn't intend to change it.   Revit makes some assumptions about what objects should be updating with one another and that's sometimes frustrating.  Also the full interaction is dangerous when bringing in new users; MUCH more caution and supervision is needed.

Overall Revit is just another tool.  The nice parts are really nice, but the reality is we still need paper plans as our deliverable.  Revit CAN make them more reliable, but only as much as the user can do.  I see project teams getting smaller but smarter, so compensation/manpower would seem to be a wash.  Revit has not been developed with the capabilities of other programs yet; it'a a bit like using ADT 3.3 back in the day.  In our context it's just not ready to be labeled the primary software for what we need to accomplish, recession or not.  That being said, I'm looking forward to the day when its capabilities & content catch up.