ME3 had the gameplay, just not the structure. ME2 was the peak with its episodic structure and an ending that appreciated and took care of all those previous episodes (to a limited point).
ME2 was great because it felt like a star trek show episode every time I played it at night. Had the continuing characters with their own arcs, a episodic small stories that weren't generally too high-concept, but entertaining per se and had conclusions of their own, without breaking the overall plot.
ME3 just felt like this immense gritty, pain filled, grimdarkian big huuuuge episode, breaking us down each time the Reapers destroyed yet another planet or another station, giving us time just to salvage something that could bring us to a comeback that never actually paid off at all... It was an emotional Titanic.