So lets talk about the phone itself now that I have gushed a bit regarding the update options...
The internal specs are pretty standard fair for a top-end top-shelf device released at the end of last year with only one notable exception which I will mention in a moment:
Processor: Qualcomm Snapdragon 800 MSM8974AB Krait 400 based Quad-Core processor clocked up to 2.3 Ghz
GPU: Adreno 330 @ 550 MHz
RAM: 2 GB of RAM LPDDR3 RAM @ 933 MHz
Storage: 16 Gb eMMC ver 4.5 Storage
Rear Camera: Very very good 13 MP Back-Side Illuminated Sony Exmor camera with Dual Phillips LED Flash
Front Cam: Excellent 2 MP Back-Side Illuminated Camera (I realize the mp count on the front cam seems low but picture and video quality I have found to be very good)
Screen: 1920x1080 5" LG-built IPS Display w/ Corning Gorilla Glass 3
WiFi: Wireless-A/BG/N 11.AC supporting both the latest 5 Ghz wifi-n band and 2.4 Ghz band. (During testing, I noted improved speeds on the 5 Ghz band)
Celullar (Phone): GSM 850/900/1800/1900
Cellular (Data): WCDMA 850/900/1900/2100 HSPA+
Other: GPS, A-GPS, & GLONASS, FM Radio, WiFi Direct, Bluetooth 4.0, Orientation Sensor, Magnetic Compass
Ports: Micro USB 2.0 / OTG, 3.5mm Headphone Jack, Full-Size SIM
Okay... depending on your perspective the specs my sounds a bit ho-hum as several chinese phones feature similarily good hardware. Let me point out some differentiators and I will oft reference the Nexus 5 ($350) as a baseline comparison as the two units are similar:
The processor is the "AB" model which is beefier than most other Snapdragon 800 chips... How?
2.3 Ghz max clock vs 2.2 Ghz on other Snapdragon 800's
The Adreno 330 GPU is clocked at 550 Mhz vs 450 Mhz
Finally the ram is clocked at a ludicrously fast speed of 933 Mhx vs 800 Mhz.
This is a notably faster processor than the Snapdragon 800 found in the Google Nexus 5 phone which is priced anywhere from $40 - $100 more depending on where you are getting your Mi3 from.
And there is more to like...