Well, I received the Lumia today and had some time to play with it.
Short answer - I'll likely return it next week and revert back to the iPhone.
The screen is absolutely amazing. Windows 10 functionality is fantastic. In fact, once all the updates loaded and installed, this phone runs very smoothly. I love how apps are organized. By comparison, iOS is simply an organizational mess (apparently designed by an 11 year old girl, albeit talented. Pastel colors abound). Tiles are very neat and the list of apps functional and clean. The camera is simply the best I've ever used. OneDrive and Office integration is unrivalled. Outlook, in particular, is terrific and I could see myself using the app extensively on the go and not necessarily put off emails until I return to base camp. I travel internationally and having dual sim is a plus, for sure. Battery capacity and charging time are second to none. Native apps are some of the best out there, bar none.
So, why the hesitation? Third party apps and lack of key functionality to which I have become accustomed.
First, missing apps I actually use: American Airlines, OptionsHouse, Rover.com, Amex, Kenmore Alfie, Chase, and a handful more but less important.
Second, mobile payment solution isn't offered. No way to store credit card data for web purchases, passwords aren't remembered across devices as well as they should be. No mobile boarding passes supported (although I found an app that promises to open and save them). Poor integration with Surface Pro 4 (which I absolutely LOVE by the way).
Question for the community. Do you think the app ecosystem will improve in the next few months? Universal Apps maybe? Is Microsoft working on the missing features I've described? Are these features already there and am I missing them as a newbie?