I have used Feria on and off for a few years and have had very good results with it. (Mostly the Power Reds)It is a little more drying than most permanent hair color but if your hair isn't too abused prior to using it....it should work fine.
I think that many ladies run into trouble when coloring their hair because they either pick the wrong shade (trying to lighten more than 2 levels etc)or are coloring on previously chemically treated hair. That can definitely affect the end result.