Do your instructor rating if you are passionate about flying and want to give someone the gift of being able to fly an airplane. Dont do it if your looking just to build hours.
I work in a very busy flight school and there are two types of instructors. The mature instructor that wants to impart his knowledge and inspire student to fly.
The others are instructors waiting to get picked up by a airline and just do the minimum instructing.........
Its VERY VERY hard to get a job as a new instructor especially with NO instructor experience. It took me a year and a lot of networking. The school that taught me couldnt offer me a job, but they did help me in giving me contacts and suggesting schools to contact.