I'll give it 2 stars only because it actually does exactly what it professes to do, but it only uses Celsius and Farenheit. No Kelvin, Rankine or Reaumur. However there are plenty of other apps that convert units for pretty much every type of unit conversion besides Temperature (Length/Distance, Weight/Mass, Area, Volume, Currency Exchange, Fuel Consumption, Time, Hex/Dec/Bin, etc.. etc..). I personally use ConvertPad myself, but have heard good thing about Unit Converter, both of which does a whole lot more at or near the same price for the pro version and converts magnitudes more.