I think that we're going to be surprised with first performace reviews... Better cpu, better gpu, higher speed ram, one more hour of battery, and especially, much faster ssd speed, can make this update very important!
Only one port isn't an issue for me (TB3 would have been welcome, but usb is the standart, and 3.1 gen A speed is enough).
The real lack for me is the 480p facetime camera, but I suppose because of display's 3mm thinness (50% less than an iphone), they haven't been able to introduce an hd version (not hd facetime on a retina display...).