long answer: yes, but it wont go back to your original color.
I have used color oops twice and have been satisfied with the results. I have brown hair and i tried to dye it darker and it came out WAY DARK, like black. I used color oops and it lightend my hair to a med/light brown.
I would say, it would be good to use, if you intend to recolor your hair to another shade because there is really no guarantee of how much it may lighten your hair.
Now i found that AS LONG as you follow the instructions right down to the T then you will end up with the expected result. Bearing in mind that it does not revert hair back to it's natural state (which is impossible when using permanent dyes) but it will remove the last dye that was used.