Got this today, so not miles into it yet - but i'm running around the shire as Sam and Frodo having completed the prologue and i have to say i'm geeking out on the whole LOTR-ness of it. The music is the official soundtrack, so running around to the same tunes as the film is epic - and i've hardly scratched the surface!
The collection bit seems the same as in the previous game and demo i played, not sure what half of it is for but guessing that'll become clear - believe you can craft new weapons and armour from it though!? Not sure if the novelty of the Lego part/gameplay will rub off before the end, but the fanboy part of me should definitely ensure i get to the end of the game, really impressed so far!
EDIT: Strongly suspect this is a 'you had to be there moment' but you haven't lived until you've had your very own 'sheep race' around the shire - i was sceptical as to how much fun co-op would be in the game but that was worth the entry fee alone (ignoring the fact i got this gratis)...! One of my standout gaming moments of this year, classic!