I bought my duel sim unlocked 950 XL at a Windows Insider event at the 5th Ave store in New York City roughly two weeks ago.
I have had very few problems with it. I did reset is once (edit: twice) because I was having problems with Text messages on T-Mobile. Actually, I do still have an issue sending pictures/video via text, but I firmly believe this is an issue with T-Mobile.
I have taken pictures, and while I'm am no photographer, I am happy with the pictures. I've never gotten an error message taking photos.
I have taken video in 4K, HD and HD slow motion... no errors, no problems.
I have four email addresses connected (outlook, Hotmail, exchange and O365). My calendaring, people and inbox apps all work fine.
I have Amazon, American Express, Amtrak, Authenticator, Blam!, eTrade, eBay, FlightAware, IHeartRadio, LinkedIn, MyRadar, Netflix, Network Speed Test, Office 365 Admin, Office Lens, OneDrive, PayPal, PDF Reader, Remote Desktop, SkyMap (Free) Skype, Skype for Business, Skype Qik, Telescope, Translator, Twitter, USAA, Waze, Xbox One Smartglass Beta and Xim installed and working fine.
The only app I've run into that doesn't work properly is Insteon Hub. They haven't fixed it yet.
I am in the Windows Insiders program and do have the latest build installed 10.0.10586.36, but I must admit, I did have to reset to install this. I'm pretty sure they fixed the issue and if I had waited, I would not have needed to reset.
I've used Continuum, and I like it very much, although I don't have a great need for it.
I haven't noticed any "Loading" or "Resuming" dialogs that some people have occasionally complained about.
Cortana works great! She always answers me. I get in my car, the phone connects, no problem. I say "Hey Cortana, give me directions to X" and she does. I say "Hey Cortana, remind me to get Milk next time I am at Shoprite" and it works. Saved my bacon a few times.
To be honest with you I really like this phone. It's a nice size, it charges wirelessly, the screen looks great and I have been pleased with both the operating system and the software I've installed.
I will admit, I like Microsoft products in general, so I wouldn't consider this an un-biased opinion, but my brother has and iPhone 6s and I wouldn't buy that thing. The home screen and lack of a back button drives me nuts. I like the Live Tiles much better, but I do recognize that it's a matter of what you are used to and what eco-system you are using (gmail vs outlook).
I really don't understand these negative reviews I've read. I haven't experienced most of the ones described. I always have to wonder if it's a PEBKAC problem (problem exists between keyboard and chair).