The idea that a dSLR is good because, and only because of IQ (image quality) is a common misconception. I also used to deride casual photographers who are shooting only jpeg on full automatic with crappy lenses.
IQ is such a dead horse that it doesn't need any more flogging here. What is acceptable IQ for you isn't someone's else, bla-bla-bla. There are dozens of reviewers shooting brick walls for you to compare. I just want to stress that
usability and the pleasure of using a reflex camera is unmatched, (currently) leaps and bounds above anything else.
First off is the joy of looking through a real viewfinder. Of course the full size 5dMKII viewfinder is much nicer than the APS-C cramped viewfinders, but even those are a million time better than any compact camera viewfinder - or LCD screen for that matter (new EVF cameras may change that but I haven't tried them).
Second is the responsiveness. When I take a picture, I want to be able to take a second immediately, without any delay - just like with a film camera. With a PAS I need to wait 1 or 2 seconds with all controls frozen before I can use it again. A huge PITA for me. The dSLR never interferes with you, it will do the writing in the background, power up and down instantly (at least since I replaced my EOS 300D).
Joy of use. Freedom. Non-inteference. Given that the entry-level dSLR from Canon/Nikon with kit lens is in the same price range as a G12, I totally understand the soccer mom who buys this kit and keep it in full auto mode and may only use 25% of its potential. It's still way more friendly and intuitive than most point-and-shoot cameras.
Now if you don't want to compromise, you can have the perfect usability of a reflex camera with the amazing IQ of the full-size sensor and the fantastic L lenses with the 5dMKII.
The bottom line is, it's a great tool, just too heavy and expensive - hmmm, wait a minute.. that sounds just like the BMW 1200 Adventure that so many people are choosing for their trip..
Laurent