Keyword and default arguments are quite nice. The main thing thats stopping me from switching so far is the new collections library-I realize its overall a good

Keyword and default arguments are quite nice. The main thing thats stopping me from switching so far is the new collections library-I realize its overall a good change (once you get past implicit CanBuildFrom[Repr, B, That] everywhere), but its a non-trivial amount of work to switch things over (which I will have to do eventually anyways, of course)