The synchronous motor made really accurate timekeeping available to everyone. Clocks driven by synchronous motors are never more than a few seconds fast or slow, and over the long term are even more accurate than modern quartz clocks.
Synchronous clocks are also virtually silent, very reliable and extremely durable.
Synchronous motor clocks do have disadvantages. Firstly, they need a permanent connections to the mains, so if you want a wall mounted clock in a particular place you may need to run extra mains cabling. Secondly, and related to the first, they are not portable without disconnecting them. Thirdly, if you suffer a power cut, all your synchronous clocks will stop and need resetting. It passes through zero again at the start of the next cycle.