What is garmin plus?

I am a garmin forerunner 45 user. I am running casualy and i am using my watch to plan and create custom workouts. I review the distance, pace and HR as a feedback for my workouts.

Every day in this community i see people complaining about garmin+. Can someone explain what is this and why people complain? What can you do with Garmin+ that you can't do without it? Is it significant for you? What's the reason you own a Garmin watch and how garmin+ makes your watch worse than before?