I finished the game today, clocked at 71 hours with 89% complete stat on my save file. I did everything I found, exluding the tasks category. Also I visitied about two thirds of all the planets, but they only give a tiny ammount of a rescource or exp, they never lead to any side quest as far as I know.
I enjoyed the game a lot, I had no real problems with the writing throughout, I liked most of the quests even though not many were as exciting as the ones from previous games. The whole experience felt a bit flat.
The ending left me wanting though - none of the big questions got answered: where did the Kett come from? What about the precursor race? And the Scourge? You only get bit and pieces but it never comes together to a coherent bigger picture story. And the similarities to pervios games themes is a let down - you basically have new Collectors, new Prothean technology and a new Crucible - a magic button that will save everything even thoug you have no clue how.
Also finding a new artificial planet seemed like a huge cop-out and also Halo derivative idea (the planet is basically a Halo, but spherical).
I would love to hear other opinions, if you finished the game.