@davidsvson.
There are a lot advantages. Mostly ease of setup, without having to code animation controllers yourself, especially for fun things like blend trees.
I like to roll my own though 'cause sometimes it's hard to get Mecanim to do what you want. Mecanim was really made with 3D animation in mind, whereas I personally like to handle my Spine animations like PlayStation-era 2D sprites.
If Mecanim is what you're used to, it's definitely a good thing to have.
If you've never used Mecanim before, expect to spend some time watching videos and searching how-tos to learn how to use it, as with any part of Unity.
