Macworld magazine just published a review of MindManager 6 for Mac OS X, which calls the program "a strong addition to the existing slate of Mac brainstorming apps." The reviewer really likes the way that Mindjet followed Apple's strict guidelines when creating this clean-slate application (not a port of the Windows version), which resulted in a program that "feel(s) as familiar as Apple’s Pages and Keynote."
On the negative side, the writer points out that this initial version of MindManager for the Mac doesn't contain all of the features of the Windows version. In particular, the Windows version currently offers a higher level of Microsoft Office integration. But this will probaby be corrected in future releases.
The bottom line? Macworld gives MindManager 6 for Mac 4 out of 5 "mice" (sorta like stars).