The reviews for Special Effects are largely positive, with most reviewers stating that the color is more vibrant and longer-lasting than similar products. The only negative is that the dye will stain porous surfaces permanently and if it gets on skin, the staining remains for a day or so.
I have heard that it is a very good product! It is supposed to clean up very well, fast, and efficiently, easy to remove from skin, etc. I have also heard (from people AND reviews) that it is great, and very quick and easy to do!