I live about 10 minutes from the show. I think I have gone to every Columbus show for the past 10 years (Except 1 as I was out of the country). It is the only show I have been to but It is a good one.
The laws in Ohio don't allow smoking indoors but some people do gather outside to smoke. There is a covered area that people hang out at. There is no tent provided and there is no slow smoke competition.
I hear that the Columbus show is a bit smaller than some others but I have nothing to compare it to as its the only one I have been to.
Some bigger vendors such as Smokingpipes.com, Smokers Haven, Great Estate Pipes, Monjour International, the pipe tart as well as many estate sellers are in attendance.
As far as custom pipe carvers there are quite a few that have been in attendance the last couple years such as Premmel Chheda, Bill Shalosky, J&J pipes, Ryan Alden, Jason Cochey (Briarbird), Joe Hinkle (solomon pipes), Nate King, Royal Oak Pipes, RC Sands, Scott Thile, Thomas James, Joe Nelson (Old Nellie), Ian Walker (Northern Briars), Dave Huber (DSH Pipes), Clark Leyton, Tim West, Split Beard and probably some others I forgot.
Hope this helps give you guys an idea of what to expect. Feel free to add any vendors or carvers that I may have forgotten.