idk

My long story short: had the 18, sold it, missed it, bought it again and will hold on to it for dear life now. I also own the 14, 35 (1.4) and 90. I hardly ever use the 14 and might as well sell it. The 18 and 35 I adore and use most of the time. The 90 is simply magical. I sometimes deliberately take it out and try to find subjects for it.
 
Here's one taken with the 18mm.
 

This thing is sharp. 
 

I think that 18/f2 is quite useful and enjoyable for street and people, but not very useful for brick walls.