When I was on a Windows based computer I thought Outlook was the greatest thing since sliced bread, especially when paired with the Plan Plus soft are from Franklin Covey. Finally everything that could be done in my Franklin Planner was being done on my PC. It worked great, until Apple switched iCal to the Cal Dev. Then I had several different calendars rather than categories and the Plan Plus software didn't recognize that. So I abandoned that, but was still able to use Outlook, just now with more calendars rather than one calendar with color coded categories. Now all the categories had to be their own calendar. Plan Plus only recognized one calendar, not or 7 different ones.
In 2011, I switched to the Mac and I got Office 2011 for the Mac because finally there was Outlook on the Mac. I still love Outlook, but unfortunately it doesn't play well with the iPhone and the iPad since it does not support the format that Apple now uses. Overall I do like having all my calendars, contacts, email, tasks and notes all in one place. I do like the fact that the mail portion will work with iCloud, I just wish everything worked with it. My solution is that I maintain not only iCal/Mail/etc, but I also maintain Outlook calendars, contacts, and tasks. I like that Outlook notifies me with a pop up when a new email comes in, mail just beeps. Both Mail and Outlook provide a count of unread messages, but Outlook also shows an unopened envelope if I am in another app. In some ways it is better, some ways the iCal/Contacts/mail work better for me, in some ways Outlook is better. I wish they all could work together and if they could it would be awesome.
One of the BEST features I like about the Mac version of Outlook is a little talked about feature called My Day. It's a pop up app that shows your days appointments and tasks, without opening Outlook. One of the things I like is that it shows tasks that are in progress meaning they have not just a due date, but a start date as well, and those tasks appear inn your task list starting on the start date. Too many apps on both the Mac and PC seem to just go with the Due Date. I love having start dates on many tasks because they may take a few days to complete. An example would be something as simple as buying a greeting card. The persons birthday is a set date, but I will set up the task with the due date being the actual birthdate, but the start date might be a week earlier. A week before the birthday the task to buy or send the greeting card will appear.
Someday I hope that there is a way that Outlook will work well with the iPhone and iPad.
I haven't talked a lot about tasks, Outlook does handle them, and iCal also has a task list, but for me I do use and Love OmniFocus. Since moving to the Mac, I learned to use and love OmniFocus for my task list. I still maintain a task list in Outlook and iCal, but will probably continue to rely mainly on OmniFocus. The tasks that I maintain in Outlook and iCal are primarily the repeat tasks.
That's just my take on the whole Outlook thing. I think it is a great app, but the Mac version could be a little better and play nicer with iOS devices. The Windows version plays very well with iOS, so I can't understand why the Mac version can't.