The ending was weakened by the fact we didn't get to play as Phelps for the last couple of cases. Because of that, we had a little distance from him and, when he was killed, it didn't hit as much as it could have had I been playing as him the whole time.
It also doesn't help that we didn't get to see his body so I couldn't be sure he was dead. I was half expecting it to turn out that he wasn't dead at all and the funeral was just a formal thing like when someone is lost at sea and presumed dead.
It was interesting and believable that the "bad guys" seem to have gotten away with it and that the good guy died.
I'm thinking the last DLC will be Kelso hunting down the "bad guys" and ending with him arresting/killing the crooked vice cop, though.