There is not a large pool of jobs for astronomers, so it can be sometimes hard to find permanent jobs
There is a lot of schooling involved
You may not ever discover something new to contribute to science
You have to work alone and work long hours
Advantages
Most astronomers have a fair bit of freedom to pursue whatever research interests them
You get a chance to discover new planets, solar systems, and life forms
You get to observe and study the wonders of the universe
Once your research on a particular topic gets published in the technical journals, it will be there as a resource for someone 100, 200, or even 300 years in the future!