Can the Garmin Forerunner 55 replace a personal coach for half-marathon prep?

Garmin is one of the most popular brands in the fitness tracker market, and the Forerunner range is particularly popular with runners (I'm a big fan of the Forerunner 955). Designed with running front and center, all the Forerunner watches focus on accurate GPS tracking, detailed performance metrics, and tools that help runners plan, monitor, and adjust their workouts over time.

Watches in the range differ vastly in price as well as what they can offer. There are entry-level models that...