Unless I utterly misremember, this is the second year in a row where my Bike To Work Day commute has involved precipitation ranging from "stinging" to "torrential" to "biblical".
I need a shell that is actually water resistant; the old cheap one from Nashbar looked and felt more like a wet tee-shirt by the time I arrived at the office. The sleeves did a good job of supporting sloshing puddles around my elbows (Yay, recumbent riding position!); allowing arms to hang straight down and loosening elastic at wrists produced copious quantities of water pouring over my hands.
Wool socks and SPD sandals were a good choice, though. I'm using that combination for most of my cycling at this point, as it seems to Just Work for most applications.