Hello Rod,
Like you I'm also Outlook and Microsoft based. I tried out the PWA twice in the last four months; the second time I really liked it. For integration into my daily GTD the right sidebar in the Outlook PWA is very useful. Not only does it show my calendar, which the desktop Outlook already does, but it also shows a proper Todo interface. You can also drag an email over and add it to the calendar or Todo, then edit any text to make it a proper next action. This can help when clearing your inbox.
In the calendar "app" the board view also looks like it has potential. Instead of just showing your calendar, it can add additional items, such as a view into your Todo, or other pertinent information. This can potentially be a good dashboard for your day.
I stopped using it though. I have one IMAP email account configured in the desktop Outlook that the PWA does not yet support. I also experienced a couple stability issues the last time I tried it earlier this month.
I'm keeping an eye on it, I think for the two reasons above it is a better GTD tool than the desktop version.
