Those are some needless harsh words.Outlook shines when matched with Exchange, not IMAP. It's hands down the best email server-client combination in the market.
Exchange + Outlook are good about combining the information about your schedule based on the meeting requests you've received and not just the items on you calendar. Further, Outlook allows most email operations from your calendar (Reply/Forward/etc), and converts the calendar item into an email when needed so the user experience is much more seamless than using Gmail + Google Calendar.
I'm curious to know by what definition Outlook shines when matched with Exchange. At least in all of the installations I've seen, I far prefer using gmail to using Outlook. And that is before you get into the fact that Exchange seems prone to crashing.
It may well be that I'm simply not in the target audience for Outlook. What I want is to get through my email, and then get on with real work. On a typical day I arrive at work with several hundred emails in 50 or so threads to go through. I generally get through it in less than half an hour, and the reading part I can do only hitting the j and space keys. Back when I was forced to use Outlook, it took me much longer to go through much less email.
Actually it seems very likely that I'm not in the target audience. Any time anyone talks about how great Outlook is, one of the first things that comes up is how good the calendar integration is. But I like living on a maker's schedule, not a manager's one. And therefore "good calendar integration" is a solution to a problem that I really don't want to have. And it is one that, if you're a manager, you should be deliberately not inflicting on your developers. (See http://www.paulgraham.com/makersschedule.html for more on that.)