I use this instead of permanent colours, and really like the depth of colour, and also how it slowly fades out. After colouring my hair is soft and shiny. The colour coverage of my greys is excellent, and the fade/wash-out of colour is relatively slow and I tend to see regrowth before the colour has significantly washed out. I don't think the colour ever removes completely though, so I tend to now just touch up roots and put it randomly through some strands rather than a full head - but I really like the product.
I measure it out and use a bowl/brush to apply rather than using all the product at once as I have very short hair, so I can get easily 2-3 applications using it this way, just doing my roots and measuring to the required ratio.
Great product for the price.