as I noted over at RPG.net, this book is a truimpth for the OGL, and a great nod to the strength of the original books. The fact that it already went back for a reprint is strong stuff.
It's also a failure for WoTC. everyone who buys this with the intention of using it, is not necessarily playing 4e and they couldn't buy it for 4e because it doesn't exist. While it might have been possible for someone to make it for 4e, given the restrictive nature of 4e's license.... well, bless Joseph Goodman for making some material for 4e as he preps his own game system but hopefully WoTC doesn't fail to learn from this.
On the other hand, perhaps those who support the OGL through purchases such as this, as I do, are not the target audience and they want 'Marvel Zombies', fans of such dedication that they only buy 'official products'. Alas, I think that door has closed forever on them.