I never thought I would actually see Morse surpassed, but I think Lewis is more intelligent, better acted, and more subtle. Kevin Whately is a superb actor; his range of expression and mood are excellently portrayed in his mobile and interesting face, and, since Lewis' character is less morose and grumpy than his erstwile mentor's, there is greater variety too. He has not replaced Morse with a look-alike - he is Morse grown up, approachable, with the same integrity but much more comfortable in his own skin.
His relationship with his sidekick, Hathaway, is played well by both actors, and the contrast between them clear but not laboured. Lawrence Fox is maturing as an actor, and the interplay between his character and Lewis' is clever, gentle, and watchable. Their differences are marked, but their essential shared morality and goodness shines out. As Hathaway learns more about himself, policing and life, he is getting a sense of humour, and understanding that his rough and ready Geordie boss knows far more about far more than he could have thought.
I love these shows. I am writing this after seeing the first two episodes in Lewis Series 6, and if the rest of the series is as good as these first two, buy this set! You certainly won't be disappointed.
Lewis - Series 6 [DVD]