I hate the motivation loop in f2p games. It ruins the game for me. If other core mechanics are great I will tolerateit: a ridiculously giant Planetside 2 battle is fun regardless of the f2p crap. Though the way the f2p/xp skews player behavior is still a net negative.
I'll give this a shot because Popcap I guess, but it better be bloody amazing.
The point about not being able to offer easy difficulty modes for more casual players is a good one too. In a f2p game you have to pay for lowered difficulty with consumable revives or whatever. They have to pony up cash or grind grind grind.