I was an user of zeppelin for a couple of years (v0.7-0.8), we used it to run Scala Spark and the UI has a lot of bells and whistles to make it easier to use Spark, display spark dataframes and simple dataviz features out-of-the-box. It is a bit relatable to the notebook experience you would have in databricks.

I certainly felt like the use case of interacting directly with spark (through scala) and very low friction visualizations was quite nice. Not that it's hard to get that with jupyter, but batteries included, just click through the UI visualization was better for zeppelin