I'm really liking it with the only big shortcoming is that not a lot of apps supporting it, even some Microsoft apps like Groove Music, Movies & TV, Mail, etc.
I also wish it will support drag-and-drop so I can drag an activity card and drop it to another virtual desktop or monitor. It may be a little thing, but it can really improve certain workflow for other users too.
They should have focused on improving the multi-monitor experience instead.
I've been sending feedbacks in regards to better multi-monitor experience in Windows 10 for years already. Currently its good but it needs to make it better. One of the things that I was asking is to better make use of Task View where I should able to drag a thumbnail of a window into another monitor/display to move window, instead of doing the traditional dragging window from one monitor to another. Using Task View to organize windows on a multi-monitor setup makes the process more organized and faster, less hunting down window and manually dragging them.
I've also asking for better Windows Snap which is slightly degraded from Windows 8.1 Metro Apps snapping, where user can snap more than 2 apps horizontally depending on screen size and all can be resized. Windows 10 can snap on corners but you can't even resize them which is a half-baked of what we got.
Anyways, hopefully more improvements on RS5 and better integration from iOS and especially Android.