I love that it is easy enough so anyone can use, but still gives you all of your analytics information if need be! The only thing i dislike about seg was not being able to have my own dashboards created with certain variables set up as they are in our store (i had no control over what info would show).
It's perfect for any size business or even just someone who wants something simple without too much hassle getting started!! We were looking at other solutions like Marketo/Hubspot which we felt could do most things well already- however there wasn't anything specific where Segment excelled above others products out now.. Our goal here has been primarily sales funnel tracking & personalization - we've seen great results since implementing segment into our flow.-.