Yes, for one of my two accounts; the second is pretty fast, over the same network and on the same devices - the caveat is that my iOS devices are on cellular networks (long live UL data!). I was a bit surprised that my iPhone and iPad synched so quickly on my Win 10-based account as the latency of the cell network is much slower than my wifi networks. I'm tethering to an iPad and iPhone this week as I'm on the road and my Win 10-based account (which seems to be mostly upgraded to the new platform) seems to be real-time except when synching from (not to) Mac Outlook 2016 to Outlook.com.
Also, FWIW, I have two Office 365 accounts with email - one Bus Premium and one Enterprise E3 to compare Outlook.com to. The main difference is the amount of granular control and ability to control synchronization preferences plus, of course, the dozens of Admin settings available in Office 365 Bus/Enterprise. The differences in sync and features in my not-upgraded account seem significant right now - fewer boxes to tick, slower response times, and fewer features - but basically looking like my upgraded account several weeks ago. I can't offer exactly when MS upgraded my main account as I'm on the road - the People and Mail apps were downloaded just last night, so I'm poring through the differences as MS doesn't offer much in the way of "what changed"...
And, FWIW, on my iOS devices, my two O365 accounts sync almost immediately, my main Outlook.com account isn't much slower some of the time but not all of the time, and my secondary Outlook.com account acts like the portal did for two years (when it got around to it...). My paid MS rep related to me last week that Outlook.com should have most of its accounts sorted out by about March-ish, and so far I'm impressed. If I find some magic setting I'll pass it on here. I'm too old to wait too long! 😀