One of the biggest complaints last year about the Moto 360 was the "flat-tire" look. Essentially the round screen was flat on bottom, like a flat tire, and not completely round. This is actually due to an excellent feature, one that many owners should know and be excited about.
The flat-tire look actually houses an ambient light sensor. This allows the watch face backlight to fluctuate based on lighting conditions. Making it dark when it doesn't need to be at full brightness, and turns it up while outdoors to make the screen easier to see. Not only does this improve battery life, but it makes the watch just work, rather than owners having to constantly fumble through settings and turn brightness up/down over the course of an average day.
We'd love for Motorola to add that sensor to the bezel and give us a completely round watch face, but the ambient light sensor is a feature many other Android Wear watches don't have, and a feature we're glad to see returning in 2015 with the new Moto 360. Get used to the flat tire, because it isn't going anywhere. Not yet at least.