What Can I say, but a real mixed bag from the start.
Installation
After 7 hours on the "Loading" Screen I lost patience and performed a hard reset.
Once the phone came up I could not use the text option to verify my windows account so I went for a fresh install.
[/ProblemsB]
The first thing was that when I had loaded a few of my accounts and everyday apps the "People" app kept crashing, this has stabilised over the last few days and appears to be stable.
Like previous comments I like Outlook but it still needs a lot more work and the ability to customise the actions of the accounts eg: mail, calendar, tasks.
The new beta store is good but there is still problems with one Drive in that you can not add onedrive business accounts from Office 365, the preview of the office apps again can not be signed into Office 365 accounts.
Bluetooth in car connectivity is terrible and keeps loosing connect all the time.
On the whole the build has a good range of advanced settings and customisations
Battery life is poor ( but that could be due to telemetry)
The phone at time is sluggish
It is hard to end calls as the screen turns off
Powering Off the phone does not turn it OFF
Bluetooth is a mess
Some apps still are very unstable
Some apps like office 365 Admin do not work
The flow of the GUI is good but still needs a lot of work.
That's my tupence worth