Man when I heard that 15mm was getting announced I got excited, but $3k for a wide angle is just too much damn money, I might as well buy some CP.2's if I'm gonna start spending that much.
The 14mm II is an awesome lens, I love mine. Insanely sharp for a wide angle, excellent color rendition, just a great all around ultra-wide lens. But at the same time I'm sure the Zeiss is absolutely wicked, razor sharp, and built like a brick. It does take 95mm filters, which I'm sure are very expensive, but the 14mm doesn't take filters at all, so I guess the 95mm filters are actually a plus. But the Zeiss is a giant beast, absolutely huge, while the 14mm is relatively compact.
That's a tough one man, I honestly think it's going to come down to price and whether or not it's worth having autofocus.