Administrating Microsoft Teams have become relatively easier after the PowerShell model was updated to 0.9.6. But have in mind, its still in beta. There were many basic settings that you only months ago had to do trough GUI or Graph API.
I have compared all the cmdlets in the Teams PowerShell module with how you would do the same operations in Graph API. There are some things not possible in Graph, that is possible with the module and the other way around. In Graph you can’t for example change a channels name like with the module. In the module you can’t list channel messages like in Graph.
So should you use PowerShell or Graph?
The most basic stuff you can accomplish with both methods, but there can be use cases you would prefer one over the other. If you are automating with another language like Python, you can use Graph to administrate Teams. As long as the programming language supports REST calls you can administrate Teams with Graph.
I guess that in the end Graph API and the PowerShell module will have the same feature set. Im not sure, but i would think that the PowerShell module uses the Graph API in one way or the other. Graph API is one of Microsoft´s large focus areas moving forward.
PowerShell Graph API Comment
Connect-MicrosoftTeams Not applicable
Disconnect-MicrosoftTeams Not applicable
Get-TeamHelp Not applicable
Remove-TeamChannel Not applicable
Set-TeamChannel Not applicable
Set-TeamPicture Not applicable