This. I really like the orange/gray color combo that is a special only from REI. And I love how much more contrast the screen is compared to my Instinct 2X Solar (flame red color). The reddish solar panel tint on the I2X is annoying and a bit "washed out" screen. Of course besides that, there doesn't seem to be a sane reason to upgrade. Same hardware, pretty much, as the I2X. Same HR sensor, build quality. I also have a Fenix 8 AMOLED, so even less of a reason to "upgrade." But I just like the screen/look of the I3. If I got an I3, I'd sell my flame red I2X on ebay, to offset some of the I3 price. If I do get it, I'll wait at least 2 months for newer firmware to fix many issues currently on the watch (as is always the case with any new garmin watch).
Can you think of any other new things the I3 will give me over the I2X? Below is the special I3 only sold at REI: