ME2 and ME3 complete linear borefests for me.  EA got involved and did the norm for them, making it appeal to the arcade crowd, stripped most of the RPG elements away and just made it a story based shooter which held your hand.  ME1 by far and away the best experience, because it was just Bioware then right.  Had perfect exploration, amazing music, amazing story, best gear system, sensible dialogue with good character progression and firefights felt more tactical.  The whole series is still the best in history, but for me personally me2 and me3 was not a patch on me1.  
I like the sound of where ME4 is going.  Let me go where I want, let me explore distant civilisations and systems, let me choose my own ppl, stories, gear with loadouts.  Let me land on any planet I wish and let me drive the Mako where I want.  Give me the freedom of space with a story thrown in and I'll be as happy as anything.