I've been playing the Imperial Agent for a few days now. At level 10, after much consideration, I decided to go operative over sniper because it seemed like a cool class that snuck around and then stabbed people. However, after awhile I decided that operative was much too slow and had pitiful damage output, so I just thought to myself "well I tried out operative and didn't like it, I should probably go sniper". That's when I found out that YOU CAN NEVER CHANGE YOUR ADVANCED CLASS. Why wouldn't Bioware let players change their advanced class. At this point I was level 18 and if I wanted to go sniper I would have to repeat about 3 days of work. I have loved this game so far, but this is the first major issue that I have run into. I hate myself for saying this, but WoW did it better.
Don't just click things.