My assessment is as such:
WBA - Excellent
Sunderland - Good
Norwich - Poor
WHU - Shocker first half, decent second
Bit of a mixed bag in all, though I have seen enough to suggest he has the makings of a top class player. Obviously he has added stability and muscle defensively, and I think his technique is under rated on this forum. He turns into space well, and looks good when stepping forward on the attack (although he seems hesitant to do). My biggest criticism would be that he is occasionally slow to release which negatively affects our fluidity and tempo although I feel this is probably related to him coming to terms with the premier league, and will improve in time.
His passing against Norwich and WHU was disappointing, but I think some on here are forgetting the WBA and Sunderland matches where he barely gave the ball away at all. My initial impressions of him were of a hugely class midfield player who bossed the midfield, made space for himself and retained the ball with ease. The passing criticism seems rather kneejerk to make - let's remember that a bad game doesn't make a bad player.
In fact, according to 'whoscored.com', his pass completion is 83.7%. This is better all of our starting back 4, SRL, Osvaldo, Lallana, JR, Ramirez, and basically everyone else in our team except MS and JWP (who both have pass completion of circa 85%).
I have a strong feeling he will go on to become a key player for us, especially as he is just 22 and will improve.