I agree with many other reviewers that the first three episodes are great but it starts to fragment during the fourth episode and then the fifth is just plain idiotic. The final scene was just too much and totally unbelievable. It's as if someone else took over the reins and the writing ... which I have seen happen before.
All the actors were great but Ben Whishaw just dominates the piece and his acting is phenomenal ....so natural and effortless.