I burn plenty of it. We got about 3 cords of it in log/rounds from a takedown for about $70 (just paying the guy's gas, basically - we live pretty out of the way). No fooling, the biggest rounds were 46" across - I had to measure it to believe it. That stuff can have HUGE trunks.
Personally I like the stuff. Everybody seems to have this thing that you can burn freshly cut ash but I never had that experience - in my stack it seems to take as long to dry as anything else. But there must be something about that cross grain in sycamore... It's a cast-iron B**** to split, but it dries to like 22% in just a few months. And not the fooling-you kind where you test from the outside. I'm talking about re-splitting a piece and measuring the inside. It's DRY. I consider it my emergency wood for that reason. I burned a lot last winter.
But as others have pointed out it's not huge on the BTU scale. The Wood MBTU chart
http://chimneysweeponline.com/howood.htm gives it as 17.9 - better than Black Ash or Big Leaf Maple, not as good as oak and hard maple.
Me, if it burns, it's going in the boiler. I may not process it first, but anything I can get the water out of and isn't soaked in some chemical is getting lit on fire. I'm not too proud to burn certain species, and the wife doesn't like to be cold.