Goodbye Set-MsolUser, Hello Set-AzureADUser & Azure Graph API. Associated blog post is located here https://blog.darrenjrobinson.com/goodbye-set-msoluser-hello-set-azureaduser-azure-graph-api/

Get-Update-AzureADUser-GraphAPI.ps1

<#
    Get the AD AuthN Lib 
    Load the Active Directory Authentication Library
    Microsoft.IdentityModel.Clients.ActiveDirectory.dll

#>
# the default path to where the ADAL GraphAPI PS Module puts the Libs
Add-Type -Path 'C:\Program Files\WindowsPowerShell\Modules\AzureADPreview\1.1.143.0\Microsoft.IdentityModel.Clients.ActiveDirectory.dll'

<#
    Create the AuthenticationContext object
#>
    $authenticationContext = New-Object Microsoft.IdentityModel.Clients.ActiveDirectory.AuthenticationContext -ArgumentList @(
    'https://login.windows.net/common' #authority
    $false                             #validateAuthority
)
 
<#
    Create the AuthenticationResult object
    Resource is the Graph API Endpoint 

    Client ID is for Azure PowerShell ("1950a258-227b-4e31-a9cf-717495945fc2"). It's hard coded in the Azure Powershell module and can be used to authenticate PowerShell scripts to Azure AD when they invoke the Azure Management APIs directly
    Redirect URI is for Azure PowerShell
#>
$resource    = "https://graph.windows.net"
$clientId    = "1950a258-227b-4e31-a9cf-717495945fc2"
$redirectUri = [uri]"urn:ietf:wg:oauth:2.0:oob"
$authenticationResult = $authenticationContext.AcquireToken($resource, $clientId, $redirectUri)
 
<#
   Get all users
#>
$users = Invoke-RestMethod -Method Get -Headers @{
    Authorization   = $authenticationResult.CreateAuthorizationHeader()
    'Content-Type'  = "application/json"
} -Uri ('https://graph.windows.net/{0}/users?api-version=1.6' -f $authenticationResult.TenantId) 

 
<#
   Get a user by UPN
#>
$upnuser = Invoke-RestMethod -Method Get -Headers @{
    Authorization   = $authenticationResult.CreateAuthorizationHeader()
    'Content-Type'  = "application/json"
} -Uri ('https://graph.windows.net/{0}/users/skollegger@live.darrenjrobinson.info?api-version=1.6' -f $authenticationResult.TenantId)


# Get User by UPN and by Variable
$userupnurl = "https://graph.windows.net/{0}/users/"+$upnuser.userPrincipalName+'?api-version=1.6'

$user = Invoke-RestMethod -Method Get -Headers @{
    Authorization   = $authenticationResult.CreateAuthorizationHeader()
    'Content-Type'  = "application/json"
} -Uri ($userupnurl -f $authenticationResult.TenantId)


# Change a users Country and Department Attrs
 $body = @{
    country = 'Australia'
    department = 'Science'
}

$postbody = $body | ConvertTo-Json 

# Update User by UPN and by Variable
$userupnurl = "https://graph.windows.net/{0}/users/"+$upnuser.userPrincipalName+'?api-version=1.6'

$user = Invoke-RestMethod -Method Patch -Headers @{
    Authorization   = $authenticationResult.CreateAuthorizationHeader()
    'Content-Type'  = "application/json"
} -body $postbody -Uri ($userupnurl -f $authenticationResult.TenantId)