I think he did an amazing job acting that character, even the look of his face did a good job
.. I always thought he really suited that role, he does have that kind of face that has the ability to look nice and kind but then switch to also look quite sinister and evil.
A lot of people gave him stick over the way his voice sounded a bit monotone and wooden, but wasn't he just trying to mildly copy the way Vader's voice sounded??, I don't think it would have worked well as Anakin if he just did his same voice that he usually does in other film roles sounding all normal and happy. His voice to me actually makes him sound a bit unsure of himself and conflicting which suits the character, it works well for me!