If you're going to spend that much... why not just get the 12-24 f2.8? Optically its just as good believe it or not. If it's for landscape, you've no need for the f1.4 aperture, and f2.8 is still pretty fast... and it's pretty much the same price as the 24 1.4 prime.
You'd have to actually be an idiot to get the prime if you have no need for the fast aperture.
If you DO need the speed, then yes, it's a great lens. Lighter than having the very heavy 12-24 attached.
Take your pick depending on what you want it for... both are fantastic.