This is quite an interesting series of articles. I like their introduction text:
Microsoft Outlook is the Jekyll and Hyde of the Microsoft Office suite. When Outlook is good, it's very good. But when it's bad, it's a horror show.
It's always interesting reading peoples opinions about Outlook, as I've never used it myself. So really, all I know about it is that "it's not Notes dude!". A few people on Ed Brill's site had some reactions to the article from Notes users perspectives.