I loved the original Black and White. It was it's own genre, really..
B&W2 was like a mixture of B&W and "the generic RTS." They added a lot of interesting things, and made city building much more fun/easy to do. But they removed a lot of the magical charm the creature had by letting you see it's thoughts, and by so limiting it's growth. Plus, the enemy AI in the game really isn't that good.
Like every other of Molyneux's games, they have the makings of greatness--but due to one reason or another, rushing, pressure, perhaps laziness, the games get released when they're less than they could be.
B&W 2 is worth playing.. but it's also really short, and has no multiplayer (yet), and as such.. despite loving B&W and having a blast in 2.. I can't recommend anyone buy it.