I was pretty sceptical but brushing my daughter's very long, tangly hair was a nightmare, lots of tears and protests and I am sure it did hurt no matter how gently I tried to do it which was a real pain on school mornings. So I ordered a Tangle Teezer and it looks like a tacky bit of plastic (the pink is, um, VERY pink) but blimey it works. It detangles so easily, makes her shiny and it doesn't hurt. Fantastic! I know this sounds like an ad, but it isn't! Thoroughly recommend.
I got mine online - after going to dozens of Boots stores (they don't stock them, the fools!) www.tangleteezer.com £9.77. It seems quite a lot of a bit of plastic, and I was a bit disappointed when it arrived, but it truly does work. DD even brushes her own hair with it (not brilliantly but she makes a decent effort) and it doesn't hurt! Amazing.
We have one too and it really is great. My own hair gets very tangly and the teezer just glides through so I can personally vouch for its painfree credentials - Can't believe it got turned down on dragon's den but guess they're doing ok without the dragons' help!