Neymar wasn't impressive in his first season but he was coming from a different culture and he is pretty young. A lot of other brazillians/south americans do a year or two in portugal, france, Holland so maybe we don't often see their first year at a top club that often. But he also had, I forget what now, bad tonsillitis, had to have them removed and dropped a stone in weight or something in preseason so he was under weight, not fighting fit and trying to adapt.
He has seriously seriously stepped up his game this year. He had his moments last year but very rarely threatened consistently from game to game or even throughout a single game. This year he looks stronger, faster, sharper. I think he would probably have been closer to current form without the illness during preseason last year.
Tonight wasn't his best game but was still effective and a constant menace with his pace and movement. Last year it was hard to see value in his price nor the idea that people thought he could be as good as Messi/Ronaldo in the future, off this seasons performances you can certainly see that possibility.