I purchased a small/medium purple device (6.625 inch wrist circumference). It is comfortable and waterproof. The instructions/app are not the best, but it has lots of interesting data and I enjoy the stress, heart rate, and VO2 features.
While some may prefer a screen that is always on, I chose this in part because the screen is not on all the time. I don't find the device to be too bulky, and the deep purple is subtle.