I never ventured to far into Quark 5.0 as 4.11 was working just fine for my office needs - I switched to OS X and was a little disappointed everytime I had to run Quark in Classic mode - but I waited patiently for this "brand new" Quark, the one that will run native in OS X and be the fixer of all that was bad.
Let me tell you - Quark 6.0 is the biggest dog I have ever run into next to Corel's Ventura Publisher. At least that's what it reminded me of .. PDF's that were always blank or missing fonts .. mysterious crashes and complete lockups of the system ... missing files and the inability to save backwards (I tried working on a file that kept crashing in OSX so I saved backwards hoping to open it and continue in 4.11 - but noooooo - the file won't open)
As far as I can see, there are no new reasons for me to switch to an OS X version .. no "tools", nothing "better" .. it crashes more and it actually makes me dread opening it as I am starting to wonder if it will crash before I have had a chance to save.
I want to be OSX complete .. so I switched to Indesign. I thought it would be a painful experience since I had been a Quark user all these years .. but no, surprisingly it hasn't been. It open Quark files with ease (so I can work on old files), most of my printers have Indesign so output isn't a problem (and for the few that don't yet - off goes a hi-res PDF file instead - which is a no brainer with Indesign). And the once or twice that Indesign did crash - next time it opened my file that I was working on was there with all changes up to date .. now that's a program.
Quark, I love and I hate it .. but you are out the door .. Hello Indesign, welcome to my office.