Swift 2 seems to have fixed one of my biggest bugbears about Swift 1: that if you command-clicked a function where one of the parameters was the wrong type, it wouldn't take you to the closest matching declaration in the headers (as it did in Obj-C) but would instead tell you that it couldn't find the function declaration. Now it seems to work! No more having to dig through the docs for small corrections.

Dunno about exceptions, though. I've seen lots of great arguments against them on HN and elsewhere, and the error reference (or alternatively double-return via tuple, especially since you can name tuple slots) seemed more clear.