One feature I love is how it can show a result table inline, like jupyter/ipython notebook does. So you can see 2 result tables on the screen at the same time.
Another killer feature is its DB agnostism. I use it on postgres, mssql and mysql, and don't have to learn 3 tools in depth.
Missing is all the db management stuff. No session view with easy 'kill the runaway query' button. No list of tables or indexes with their sizes and usage stats. If you want that, better learn the metadata tables of each DB.
It also has its share of really weird bugs. Today it refused to accept text changes in a small specific zone of text. After closing the file, it wouldn't open it, either. I removed part of a query, and all was well again. I've got a few similar weird bugs in the short month I started using it. Pgadmin also has plenty of bugs, but at least their bugs make some kind of sense.
Oh well, I got it for free, so I shan't complain. In fact, chances are pretty good that I'll pay for next year's license. It is good,but still far from perfect.
My main beef with pgadmin4 is that the UI is sadistic when it comes to window positioning.
I'd be happy to get some relief from that, but it seems to me that it ought to be possible to make some user interface which is really cool for browsing tables and rows as opposed to just knocking off the UI from a Java IDE.
The SQL Editor and Database Manager Of Your Dreams: A modern, easy to use, and good looking SQL client for MySQL, Postgres, SQLite, SQL Server, and more.