I have naturally quite light green eyes, and as these lenses not especially opaque the end result for me is a kind of deeper olive green. Really quite lovely - but not the medium brown I was hoping for.
If you're looking for a complete colour change I wouldn't suggest these, however if you're looking for something to enhance an existing colour these are perfect. Also - their smaller size and lack of black limbal ring makes them appear quite realistic, not 'doll eyed' or 'alien' at all.
As a side note, I've found these to be exceptionally comfortable, perhaps due to their smaller diameter than most circle lenses. Even though I didn't quite get the effect I was hoping for, I'd still give these an 8 out of 10 all up.