Well, I finally got the game, was a birthday present. It starts pretty slow but after the first ten or so missions it really picks up with more enemy types (especially with more dangerous ones, the first few missions include only fairly small and harmless enemies). Of course there's slowdown but it's really impressive how much it takes for that to happen. The characters really differ a lot, Frey has stronger melee weapons and no restriction on how much he can use them though his bows take forever to fire, Freya has a large assortment of ranged attacks (including some that can wipe out an entire army, including you if you aren't careful with aiming them) and fire very quickly but the limited mana that can only be refilled by using her fairly weak melee weapons.
So far I really don't like the nunchuk thrust for dodging, wouldn't surprise me if there was a way to adjust it but the options menu has a TON of entries.