Super useful, but not consistent
What do you like best?
Symless Synergy is a solution which allows keyboard/mouse sharing across multiple computers; imagine having two laptops and a desktop on your desk, but only one keyboard/mouse. It's wonderful to not have to move from one keyboard/mouse to another, and have only one on a desk instead of several.
What do you dislike?
It's far too tricky to get this working consistently. Over Wifi, it's almost unusable due to lag. Over Ethernet, it depends on how the machines are routed to each other. A direct Thunderbolt connection works best for me, but even then, the sleep/wake modes are problematic. I've had to develop my own helper scripts and utilities just to get Symless Synergy working correctly.
Recommendations to others considering the product:
Try it, but be prepared for frustration while getting it working.
What problems are you solving with the product? What benefits have you realized?
I'm able to share a single keyboard/mouse across multiple computers; keeps my desk tidy and aids my workflow by not having to change input devices.