Entourage: Big omision in the lack of ability to subscribe to RSS calendar feeds. Most mac users use iCal because of the ease of maintaining separate calendars and the ease in subscribing to other ical or RSS calendar feeds. Entourage dropped the ball here. I would use the app if I could pipe in feeds from basecamp and google calendar. Right now the “better” exchange mail support is suspect because of my lack of my ability to link to a hosted exchange account. Still using Mail.app.
Word: nice UI, but I still find pages a more intuiive way to create nice looking docs
Excel: Still the champ here, but I have to say Numbers is winning me over when it comes to visualizing data and simply creating nice graphics
PPT: not interested. Keynote is by far the most useful presentation tool I have ever used.
If you need Office, it performs better natively, but I don’t think the $$ is justified until Entourage is the clear winner for mail and calendar. Also, I have noticed I cannot have Mail and Entourage open at the same tie without crashing Mail!