I switced back to Microsoft Entourage today after finding Apple’s Mail program that comes bundled with Mac OS X pretty much inadequate.
The management of email contacts is klunky in the seperate Address Book application. There was no way to specify a character set in an outgoing message, which was really annoying. I found features such as Instant Message Status Indicators nearly useless, and at the same time the application was missing what I consider to be important features such as a BCC line and message priority indication.
Stuff like Mail, iCal, iChat, and the Address Book are all very cool ideas with the whole integration thing and all, but the stuff is just too rough around the edges right now. I’ll keep an eye on it and hope it all improves over time.