A simple (and highly improvable) PS script to retrieve VMs informations.

Automation_SimpleGetAzureVMs.ps1

function Login
{
    $Conn = Get-AutomationConnection -Name AzureRunAsConnection
	$output = Add-AzureRmAccount -ServicePrincipal -Tenant $Conn.TenantID -ApplicationID $Conn.ApplicationID -CertificateThumbprint $Conn.CertificateThumbprint
}
function FlattenTags ($tags) {
    if ($tags -ne $NULL) {
        $result = ($tags.GetEnumerator() | ForEach-Object { "$($_.Key)=$($_.Value)" }) -join ';'
    }
    else {
        $result = ""
    }
    return $result
}

#Login in Automation
Login
$Subscriptions = Get-AzureRmSubscription | ForEach-Object {"$($_.Name)"}

$allResources = @()

# Custom class to store the data (needs powershell 5)
Class AzureResource
{
	[string]$Subscription
	[string]$ResourceType
	[string]$ResourceId
	[string]$ResourceGroup
	[string]$Location
	[string]$Name
	[string]$OSType
	[string]$VNet
	[string]$Subnet
	[string]$Size
	[string]$vCPU
	[string]$RAM
	[string]$Status
	[string]$Tags
}

ForEach ($Subscription in $Subscriptions) 
{
	$output = Select-AzureRmSubscription -SubscriptionName $Subscription
	Write-Verbose "Processing data for subscription $Subscription"
	$armVMs = $null
	$armVMs = Get-AzureRmVM
	
	foreach($armVM in $armVMs)
	{
		# ARM VM
		Write-Verbose "Processing data for ARM VM $($armVM.Name)"
		$azureResource = New-Object AzureResource
		$azureResource.Subscription = $Subscription
		$azureResource.OSType = $armVM.StorageProfile.OsDisk.OsType
		$azureResource.Location = $armVM.Location
		$azureResource.ResourceId = $armVM.Id
		$azureResource.ResourceGroup = $armVM.ResourceGroupName
		$azureResource.Name = $armVM.Name

		$sizeinfo = $null
		$sizeinfo = Get-AzureRmVMSize -Location $azureResource.Location | where-object {$_.name -eq "$($armVM.hardwareprofile.vmsize)"}
		$azureResource.Size = $sizeinfo.Name
		$azureResource.vCPU = $sizeinfo.NumberOfCores
		$azureResource.RAM = $sizeinfo.MemoryInMB
		
		$vmstatus = ""
		$vmstatus = Get-AzurermVM -Name $armVM.Name -ResourceGroupName $armVM.ResourceGroupName -Status
		$azureResource.Status = (get-culture).TextInfo.ToTitleCase(($vmstatus.statuses)[1].code.split("/")[1])
		
		$nic = Get-AzureRmNetworkInterface -Name ($armVM.NetworkProfile.NetworkInterfaces[0].Id -split '/')[-1] -ResourceGroupName ($armVM.NetworkProfile.NetworkInterfaces[0].Id -split '/')[-5]
		$IpConfig = ConvertFrom-Json -InputObject $nic.IpConfigurationsText
		$subnet = $IpConfig.Subnet.Id			
		$azureResource.VNet = ($subnet -split '/')[-3]
		$azureResource.Subnet = ($subnet -split '/')[-1]
		
		$azureResource.Tags = FlattenTags($armVM.Tags)

		$allResources += $azureResource | Select-Object `
		Subscription, `
		Name, `
		Size, `
		vCPU, `
		RAM, `
		OSType, `
		Status, `
		Location, `
		VNet, `
		Subnet, `
		ResourceGroup, `
		ResourceId, `
		Tags	
	}
}	

# output the data to the csv file
$allResources = $allResources | Sort-Object Subscription, ResourceGroup
Write-Output ($allResources | ConvertTo-Json)