Looks really cool and unique. Less humane to my disappointment, but I guess I'll have to slide since it looks much different than what most developers would create as "grass people" (which is basically green skinned people with some leaves slapped on).
The Amulet is basically what kept San alive for a brief time in the GSLs, because he was basically purchasing storms to defend his expos. It was slightly overpowered, even though I thought HTs were way more awesome than Colossi.
Unless smartphones can offer a true handheld experience a game on a DS can offer, then no, handheld consoles aren't going anywhere in the near future. The smartphone market is negligible smaller compare to the supreme dominance that is Nintendo's handheld consoles (in numbers sold anyways, smartphones is a growing market).