I havent had a chance to try this yet but i must say i'm very impressed with the look of it's user interface, and the website design too.
Their "eventing" seems a little long winded compared to constructs.
I don't get it as well, it's been years in the making going on about their java engine then all of a sudden then decide to use flixel, and the "revolutionary" way to program games thats been hush hush for so long turns out to be scratch blocks?
Still competition is usually good news for us users
I think Construct will have to be something "extra" special to compete against a free product of this quality.