Just bought the lens and all I can say is WOW. I have not had the chance to test it extensively, but so far it seems very sharp and with great colours. Images just have a certain "pop" to them.
I've instantly developed a new form of Lens Lust - Expensive Lens Lust.
This is my first decent (read: expensive) lens and there is something very comforting and confidence inspiring in such a solid, heavy, big lens. It just feels right. 
On another note, I almost bought a 2nd hand Sigma 30 f/1.4 at ORMS yesterday. Fortunately I took my camera with me - the focus was so out of whack even the salesman recommended I don't take it! Pity though, a wider fast prime is really the only thing I feel I need extra right now.
Oh, and one day a 70-200 f/4 L IS...
I've instantly developed a new form of Lens Lust - Expensive Lens Lust.
On another note, I almost bought a 2nd hand Sigma 30 f/1.4 at ORMS yesterday. Fortunately I took my camera with me - the focus was so out of whack even the salesman recommended I don't take it! Pity though, a wider fast prime is really the only thing I feel I need extra right now.
Oh, and one day a 70-200 f/4 L IS...