I'm having a hard time trying to decide on my next lens. I have never owned an UWA other than the 20 2.8 which I sold some time ago, and am not sure how often the 16-35 f4 would be used...but those reviews and images I've seen are making it a very tempting choice. On the other hand, I shoot professionally (sports, events, and the occasional wedding), and quite often in low light. I also enjoy night photography (star trails, etc) which makes the 24 L II an equally tempting offer, and something I will eventually buy even if I go with the zoom for now.
I'm looking to hear from those who have used both and the pros and cons of each.