The messages about problems on the new iMac will multiply on the Apple forums. For now, the source of problems is not yet clearly identified. However, the result is a machine very slow. The first users have pointed to the management of Flash that slow down the iMac, while others have highlighted a problem with the hard drive with rotational speed decrease.
Apple is currently working on correcting problems and especially their reproduction. The updated Mac OS X 10.6.2 scheduled for November should probably correct the problems on the new iMac.