The uniform is pretty atrocious, although I will say everything comes out of them in the wash and you don't have to think about what to put on every morning. Compared to other companies like MAC, if you're a true artist, you should be making a lot more money and Sephora's raises are barely cost of living at best. It's a good side job, but you will struggle to make rent if you're relying on this money to live.
If you want to move up, it's going to take you 10 years to get where you want to be. If you want to work for Sephora corporate, you're better off going to their LinkedIn to apply. Sephora is not about developing and moving people along, but finding good people and keeping them right where they are.