COUNT without GROUP BY

I found a novel way of doing a record count today, without using a GROUP BY.
Normally I would have joined another results set containing a GROUP BY, but it appears you can use the OVER window function without a PARTITION BY / ORDER BY statement.

The syntax is COUNT(*) OVER () AS [RecordCount]

I use it below to return the count of addresses in AdventureWorks.

SELECT DISTINCT 
      a.[City]
   ,sp.Name As StateProvince
   ,cr.Name AS CountryRegion
   ,COUNT(*) OVER (PARTITION BY sp.[StateProvinceID]) AS AddressesInThisProvince
   ,COUNT(*) OVER (PARTITION BY cr.CountryRegionCode) AS AddressesInThisCountry
   ,COUNT(*) OVER () AS TotalAddresses 
  FROM [AdventureWorks2014].[Person].[Address] a
  INNER JOIN [AdventureWorks2014].[Person].[StateProvince] sp
  ON a.[StateProvinceID] = sp.[StateProvinceID]
  INNER JOIN [AdventureWorks2014].[Person].[CountryRegion] cr
  ON sp.CountryRegionCode = cr.CountryRegionCode
  WHERE cr.Name = 'Germany'
  ORDER BY 1,2,3