Is the cheapest Sensi thermostat good enough, or should I spend more?

For shoppers who want app control and scheduling but not a touchscreen, room sensors, or air-quality monitoring, the Sensi ST55 is described across r/smarthome, r/thermostats, and mainstream tech press as a solid, no-frills pick. If you want a touchscreen or remote sensors, stepping up to the Sensi Touch or an ecobee/Nest model is worth the price difference.