Absolutely loving this game so far.  I’ve reached the end-game after a mere 65 hours gameplay!
I’ve made a Checklist in Google Docs from various guides on the ‘net to ensure I collected everything for the Treasure Trove achievement without having to follow a guide and thus ruining the experience — I certainly didn’t want to get to the end of the game and find I was missing a couple of items for the achievement and have no idea which ones were missing as I did with those poxy Orbs in Crackdown…

At 80MSP I coudln’t resist the Dungeon Pack: Seeker of the Deep! DLC pack.  I just wish all older games’ DLC was reduced in such a manner (Stranglehold’s Map Pack is still 1200MSP!)

Achievement wise I like that the majority of story-related achievements are tied to optional side quests rather than the main plot, meaning that the achievement list was pretty spoiler free for anyone that read the achievement list before playing the game.  Also, it’s good encouragement to go exploring all those optional locations.