This is a great stamp colour set and a worthy addition to any of your other Melissa & Doug kit, or indeed any stamp tools. The ink is colourful and washable. The small downside on the ink is that it doesn't simply rub from skin, it needs properly washing off.
It comes out of clothing no problem (it's been extensively tested in our house)
As to be expected, if your child stamps green then goes yellow, there is a bit of ink leakage but that is a learning problem rather than a product problem.
The casing is durable and closes tightly for transport and keeping the pads useable.