I'm all evangelical about it. Do it! Do it now! It's brilliant!
My last major clearout was a year ago, but I was more ruthless this time - I invited a very candid friend over who knows what I wear and I like her style. She sat on my bed and asked searching questions like 'When did you last wear this? What do you wear it with? How did you feel when you wore it? Isn't it exactly the same as the other red t-shirt over there? Do you really need two?'
Three big refuse bags full of clothes have gone to the charity shop - I don't have a huge amount of space (narrow IKEA wardrobe and three drawers), so it's pretty amazing that I had enough clothes to get rid of that many and still have anything left.
My clothes hang freely in the wardrobe instead of being bunched against each other, and my drawers open and close smoothly without having to cram things down. Everything is sorted into tops, bottoms, jackets, dresses. I can see exactly what I've got and I only own things that I feel fabulous in apart from a set of comfies, and two sets of exercise clothes. Everything else has gone. Ahhhh. Better than shopping...