I subscribe to "Ask Woody" which is a Windows oriented web site and just this week one of the authors, Peter Deegan, had an article about the Outlook (new). I'm pasting in an excerpt of his article. This article is for paid subscribers so I can't link to it for you or I would have.
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It’s not ready. Remaking Outlook desktop with different and new technology is a huge job that’s taking Microsoft years, and they are still working on it.
Outlook (new) is not ready for the public. Redmond is treating this like a new and complete product, but it is most definitely not. Outlook (new) isn’t even close to being a replacement for Outlook desktop for Windows or Mac.
Microsoft is rushing out an incomplete product, even though it’s missing at least one crucial feature: proper offline support. What’s more, it has a major privacy issue: login details saved at Microsoft.
Offline support Outlook (new) requires a constant, fast, and reliable Internet connection. Only in Microsoft’s Fantasy Land™ do people have that. Even good broadband has outages, let alone anyone traveling or having spotty Internet access. This includes most people on Earth.
Outlook needs to work offline with a local, synchronized copy of the data held online. That’s necessary so people can work when disconnected and also for faster access to info and as a backup. Outlook desktop has that with the very familiar PST/OST database files, but not Outlook (new), which has only a vaguely defined cache.
Microsoft’s latest promise of “offline” support is very limited and not what Outlook desktop customers are accustomed to.
Adding proper offline support means having a fast and robust database on the computer, and that’s difficult for a PWA. Microsoft seems to be hoping that people won’t notice the loss of proper offline support and will tolerate half-measures instead.
Huge privacy leak A recent boast about Outlook (new) is that it works for non-Microsoft accounts such as Gmail, Yahoo, iCloud, etc. What Microsoft doesn’t say is that you have to give it your login and password for those mailboxes.
Outlook desktop connects directly to each mailbox, with the login details shared only with the mail host. Outlook (new) works very differently. It passes your login details to Microsoft’s servers, which then connect to the non-Microsoft mailbox. All your data passes through Microsoft’s hands, and the company saves your login details."
