Yeah as the defacto Tableau Server administrator in my org, I am not happy with Tableau. Despite it's power and ability to let less-technical people generate insights from data, the administration experience as a whole is a total nightmare; purchasing/applying licensing to all installations is a disaster. Maintenance upgrades and backup procedures are also sort of wonky. For the data visualization piece, I personally feel like the software is difficult to use because it uses custom "branded" terminology for many things, so the knowledge you gain using Tableau can't often help you outside of Tableau... and then they place many features in locations that are not intuitive and thus difficult to find without documentation or prior experience.
We're a Microsoft-heavy shop, and I've been trying to get them to move to Power Bi simply because it's far more fully featured, easier to use if you're familiar with the "Windows way" of working, and has streamlined administration/installation/licensing/configuration in Windows environments.
I think Tableau Server works better on Linux, where upgrades etc. are also somewhat less painful and require less downtime.
That said, it baffles me why I have to restart Tableau Server 3 or 4 times during installation, and why I have to restart it for trivial changes more generally. For a piece of software that specifically ships with a cluster controller and full-blown zookeeper, somehow their engineers (or "engineers", as I sometimes get the impression) manage to make things that should be trivially solvable with reloads, partial restarts or spawning new workers (e.g. SSL certificates for the built-in Apache webserver) require a complete restart of the whole node.
edit: Regarding Power BI -- I feel that Tableau Server is (for better or worse) one of the killer features for many enterprise customers, because it means all of your data can remain within your own infrastructure and does not have to rely on external cloud providers. If that is not a requirement in your organisation, Power BI might make sense depending on your overall IT landscape, as well as your users' specific needs. On the other hand, if your organisation requires hosting things yourself, I guess it doesn't matter how miserable the experience is for you as an administrator. That's basically Tableau Server in a nutshell.
We're a Microsoft-heavy shop, and I've been trying to get them to move to Power Bi simply because it's far more fully featured, easier to use if you're familiar with the "Windows way" of working, and has streamlined administration/installation/licensing/configuration in Windows environments.