Their spam filter has been horrible lately. I've been on outlook.com ever since it was rebranded away from hotmail, and it was OK until recently. But the spam has gotten so horrible in the last few months, I'm trying to decide what to use next (given that I don't live in china anymore, I have choices).

It is also missing a lot of features compared to gmail, while the web UI is a bit clunky. These aren't real breakers for me (spam is); but it is hard to recommend. Is premium much better?

Owning the domain makes for great email address portability. If I hadn't read so many of your comments here over the years, I probably wouldn't suggest this, but I think a good strategy is to buy 2 domains, one for trusted entities (i.e.people you know or your bank/ credit union) and one for non-trusted entities (i.e. Amazon or commercial entities in general). Use your domain registrar's email hosting for trusted entities (add PGP for extra goodness), and use a commercial provider (e.g Google, Fastmail,etc.) for the non-trusted entities domain.

Strange, my spam filter is fine. Premium is just no ads + some extra space. I pay premium because I want microsoft to keep providing this excellent service without compromising my personal data