Ginger is a great cocktail flavor which has become more popular in recent years, particularly since the release of Domaine de Canton (a ginger liqueur). La Coloniale is as simple as the Ginger Martini but uses gin instead of vodka, which adds a depth to the drink.
What you do want to do is use a premium gin - something like Tanqueray or Martin Miller's - to balance out the ginger-botanical profile of the cocktail. Many of the value gins lack the complexity necessary to pull this drink off well. The cucumber slice is a nice touch here as well because it adds subtle freshness to the drink and works well against the ginger.