Willow's funny stuff and burning wise varies a lot between different species of it. Some of them feel very light and almost dry when they are fresh felled which can lead people into thinking it's ready before it is. Goat Willow is the complete opposite and burns really well.
Try splitting some of it a bit smaller and there's half a chance it'll take a little better than it is just now.
Also, most of those old firewood poems are pretty much just that - a better one would be (and I can't take credit for it) "wood burns, water doesn't"