Due to the ever increasing cost of Outlook it is worth considering Outlook Web Access (OWA) over Outlook.
I recently used it for a few days to see what problems users may notice when using OWA over Outlook and here is what I found;
Spell Checker - The spell chcker isn't automatic so you have to press the button - no wavy red line.
Speed - Can be quite slow if not on local network to the server
Short Cut Keys - Some of the shortcut keys do not work - Ctrl>F(Forward), Ctrl>Z(Undo), Ctrl>A (Select All)
Reminders - They're hidden away up the top often i didn't realise one had popped up
Screesnhots - i'm a lover of inserting images from a print screen within my email messages - you cant do that.
Depending on how you work the followup task list is difficult to navigate and work with.
Very easy to close the window as its part of internet explorer and not a seperate program
The Up Arrow doesn't appear to work - this could have been a bug on my machine however.
Cant overlay calendars.
Cant copy & paste appointments
Cannot Drag emails to your calendar
Can't scroll around in calendar
Cannot sort by category in todo list
Cannot drag to follow up - you have to click.
These are only small problems really, and overall OWA is brilliant for working out of the Office but when compared to the Outlook Fat Client it has a lot of missing features that i've become so used to over the years that i dont think i could live without it.