It's a pretty lengthy piece, but well worth taking the time if you have an interest in how the human brain perceives colour, what colour blindness is, and how the EnChroma glasses work. You might also want to participate in his survey after you've read through the article:
Porter's article explains the processes far more eloquently than I can. I've always been OK with Fire Engine Red, Canary Yellow, Sky Blue, and so on, but all of the intermediate and pastel colours have always been a problem, tending to blend into an undistinguished green-red-brown-pink-purple. Many colours that are dramatically different to most people are virtually indistinguishable for me.
The best description that I have been able to explain the EnChroma experience is like sitting in front of a well-adjusted colour TV, and then turning the “Colour / Saturation” settings up by about 25% – all the colours are “real”, but they become much more rich, vivid and saturated. Pastel shades which have very little colour intensity to my unaided eye now show much more saturation, with what were previously subtle differences between two shades now becoming much more distinguishable.
Green traffic lights are a good case in point – they've always looked white with a green tinge to my eye (like a fluorescent tube), but now they are definitely green. The other big “wow” factor for me is the sunset sky – I've always been vaguely aware of various shades of red, orange and pink at sunset, but they are generally very subtle and it’s only rarely bowled me over, but with the EnChroma lenses, every sunset is a delight! (I don’t know if this is what I've been missing my whole life, or of I'm seeing something that people with normal vision don’t see, but whatever it is, I really like it!)
But beyond the main EnChroma / Colour Blindness theme, there's some fascinating stuff about the impact of language and culture on our perception of colour. Did you know that the ancient Greeks didn't think the sky was blue? Or that there is a tribe in modern-day Namibia who can easily see the one square in the first pattern below which has a different shade of green (I sure can't), but struggle to see the blue square in the second pattern? Amazing stuff!