I've heard great things about HS. i never got round to playing it because i couldnt be bothered with all the new releases and lack of trophy support.
but i have heard that Ninja Theory originally penned 3 scripts and it was intended to be a triliogy. but apparently the lack of sales success meant they didnt go ahead with the second game.
personally i'm not sure Santa Monica should be in charge of the series, i would rather see Ninja Theory be in charge of it, for consistancy. and i'm not sure i like Santa Monica without David Jaffe.