I've got it already, thanks to Play.com posting my copy on Monday.
Only played it for a little while, but I'd say on first impressions that it seems better than the last one. The first Story mode level isn't that great, but the following level is far better. Barely touched the Arcade and Challenge modes yet though, but the old "Behead The Undead" series of challenges is back with a twist, with the Bronze one being against zombie monkeys, some of whom are armed, and the Silver one being against re-animated cow carcasses.