The let down for me, as many have stated was definitely the ending. Coming off a Mass Effect 2 induced high, I had very high expectations as to how this trilogy would end, and it just didn't live up to them. Regardless, the journey to the end is still fantastic and entertaining. Definitely recommend starting from the first game though! Also, might be a good idea to get the DLC for this one, as I find it adds to the experience (I got quite attached to the characters) but of course, not necessary.