The official language in Liechtenstein is German. The spoken language is an Alemannic dialect.
The people in Liechtenstein share their dialect, their cooking and their mentality with the other Alemannic regions: Vorarlberg (Austria), Swabia (Germany) and the German speaking part of Switzerland – with little differences.
Outside the family and collegues in most German speaking countries you have to use the honorific word "Sie" to address people. In Liechtenstein people mostly use the more collegial form of "Du", regardless of who they are adressing. So don't be upset, if people use "Du" to address you – it's not meant to be impolite!