Shopify Plus is the premium version of Shopify, designed for top-tier brands that do a high volume of sales on a daily basis. While not necessary for every merchant, Shopify Plus does have some great features that enterprise-level brands can’t live without.
In terms of advantages, Shopify Plus offers superior customization options (including checkout customization), your own success manager, access to premium apps, and more.
As for the disadvantages, Shopify Plus is of course more expensive than the standard Shopify plans. Also, to take advantage of a lot of the customization options on offer, you will need some web development skills or help from a developer.