I've been using the new Outlook for some time now, and many of the redeeming qualities of its predecessor are gone while its negatives remain or, in some respects, have been exacerbated. While the new client is betaware at this time, the prospects for meaningful improvement in a reasonable period of time are dim.
My one great need has been rule-settling and filtering. I get hundreds of emails a week, and, while Outlook isn't superb, it's the best of the ones I've tried (Thunderbird, Claws, etc.). If there is a client that can sort every message received into folders by sender and all in a few lines of code, I would greatly appreciate being informed of it.
The secret sauce there is sorting emails by multiple address books - different emails in address books go to different folders. So email from the screened in address book, goes into the inbox and emails from the Newsletters address book goes into the newsletter folder. And so on.
The difficulty for this type of setup is sometimes you get email from companies that send all their emails from the same address - promotion, receipts, etc - so if you screen them out because of a promotional email - you might miss out on a receipt. The answer to this is to make a rule for that domain, using subject line filtering.