That first half was simply sumptuous and like others have said, we've rarely seen better. The great thing is that we come flying out of the traps these days, instead of under Pellegrini, when we were cautious and always started so slowly. Another great thing is that we're winning the 50/50 balls this season, which we weren't last. So many other good things - Kev is getting back to full fitness, Otamendi, Stones (and then Kolarov) look imperious, Silva & Sterling are both playing incredible stuff, Nolito is such a clever player and Dinho is doing what Dinho does. Willy had a couple of iffy moments but his distribution was by-and-large impeccable, leading to us keeping possession and setting up attacks. Also he sees things quickly and acts, rather than Hart standing there and taking time to make the wrong decision. finally, how good did Nasri look when he came on. We can keep two of the the five marked for sale so I hope he's one of them.
The downside was that Zab was beaten far, far too easily for the cross that led to their goal. He's just not the player he was. Sergio is still not quite there either, despite his CL hat-trick. You can see his frustration at times. Finally, we still haven't quite eliminated that tendency to go to sleep or relax when we're a goal or two up and in all the PL games this season, we've followed the same pattern - score early, fail to kill the game, relax and allow the other team back in, then kill it at the end. I'm sure that'll improve though as Pep builds up our fitness and levels of concentration.