Indeed, I've read quite a few reviews on them. Most very positive, a couple commenting that the SQ is not up to scratch - but I don't think you can go wrong for £40~50.
I had a play around with the sound on the iphone this evening and noticed that the EQ was on and set to "Rock" I turned the EQ off and now sounds much better. The treble is now a lot clearer. Again, I'm assuming they will change slightly once worn in but very happy.
Before I got these I've demo'd a pair of Sennheiser HD 218 which I found to be very quiet, I had to turn my iphone up to around 90% before I classed as loud - in comparision the K450s are around 65~70%. They didn't sound to bad, but no where near as good as the K450s.