The IR (R) - which used to be called the IMC Rating - is a very good rating to add to your Private Pilots License. It allows pilots to get out of trouble should the weather close in by flying in cloud and performing instrument approaches down to the published minimums.
The course is 15 hours training and covers instrument flight (sole reference to the instruments), navigation and precision/none precision approaches to airfields. There is also one theory exam similar to the exams covered in the PPL.
