Both the Tiguan and Volkswagen as a brand have earned middling scores for reliability across a selection of surveys. Owners tend to praise overall build and material quality, but occasional mechanical and electrical gremlins can sour the experience.
The engines and many additional parts used in the Tiguan are also widely shared with other Volkswagen and VW-Group cars. That means you shouldn't struggle too much to find replacements if something goes wrong.
Add an extended warranty when you buy your Tiguan to protect yourself against unexpected repair bills.