It'll make a man out of you, and a privy out of your shop, as others have indicated. It's loaded with water, some of it pretty stagnant and fragrant, and it's also interlocked, soft and fuzzy-grained. Don't worry too much about the fuzz as you rough, it'll diminish when the wood's dry. It will teach you how to present an edge, and how sharp it should be, so experiment with your free wood. You can cut it and produce continuous shavings, it's just not as easy as with maple or cherry.
It looks great when dried and re-turned, though it will suck a lot of finish before the shimmer emerges. The thirty or so bowls I got out of my downed willow practically jumped off the shelves. It also has thick, cork-like bark that makes for wonderful interupted edge stuff, but you'll want to stiffen the soft layer with some shellac or CA to protect it as you turn and from customers when they handle.
It's almost bulletproof in drying, so no coatings or special care required. DO NOT DRY IT IN THE MICROWAVE, as it will quickly make the room uninhabitable, and the microwave used a permanent part of your shop as well as an endless joke for the spouse at parties.