I've used Microsoft Outlook as my preferred email client literally from the day the first beta was released back in the late 90's - I think the initial version was called Outlook 97. To me it was a breath of fresh air, as I could do all of my email and calendaring from the same window. My company was in the process of rolling out MS Exchange across the enterprise, and so Outlook was a huge improvement over having to use the kludgey combination of the MS Exchange client along with Schedule Plus - anyone but me remember that one?
Over the dozen plus years since then I've used each and every version of Outlook. Functionality-wise it keeps getting better and better, especially when you've got an Exchange server on the back-end. However, at the same time its footprint seems to get bigger and bigger with each release...sometimes I go into Task Manager and see that it consumes half a gig of RAM...WTF does it need half a gig for? And the time it take to load the software on my machine seems to increase the more I use the product...somehow all these plug-ins get installed on my behalf and I'm forced to stare at the Outlook splash screen waiting for each of these to load - a real exercise in patience. And finding out how to disable these plug-ins is no easy chore, and also can only be done within Outlook itself. This ended up being a major headache for me a couple of months ago when my Outlook was hanging every time I launched it and the culprit was this antivirus plug-in that had been recently updated. Suffice it to say that it was quite the challenge to finally fix this problem - it took multiple attempts before I could disable the plug-in within the short time window between launching Outlook and having it start hanging again.
I've written in the past about how I've reduced my dependency on Microsoft over time, and now I'm pleased to report that I've finally ridden myself of this overly engineered, bloated piece of software called Outlook. I've been using Gmail and/or Google Apps mail for the most part anyway these past few years, and the native web versions have also gotten a lot better over time. Offline viewing has been available for the past couple of years; a few months back they finally allowed you to disable "conversation view", which for the life of me I could never get used to; and they even implemented a few new features such as notification pop-ups that you'd normally only find in traditional desktop applications. And I've also come to appreciate the way Gmail uses labels as an alternative to folders - it's actually a much more elegant solution than having to manage a folder hierarchy. Since I've made the switch I've never found a need to go back, and my laptop thanks me for it!
As far as the other functions of Gmail/Google Apps go, I think it handles my calendaring and contact management needs just fine. A weak point in my opinion has always been its task management. There have been some recent improvements here as well, but features I've grown accustomed to in Outlook such as the ability to create recurring tasks are still not supported - not a show stopper, however. Getting rid of Outlook has also made it easier for me to synchronize data to my mobile devices. Since I've been using Android for awhile it's great never have to think about synchronizing my mail, calendar and contacts to my Nexus S, and there are some great 3rd-party solutions for syncing other types of data such as tasks and notes.
So goodbye Outlook, my old and dear friend....I don't think I'll be missing you. But despite all the frustrations I've had to endure, I guess it could have been worse.