McLaren appear to be just mildly evolving on their previous aero designs, from all the way back to the 18, which I believe never raced. That car really led the way for a lot of changes in the past couple of years.
While the McLaren quite different from any other F1 car it appears to be quite similar to what they've been doing. Note that they haven't attached wings to the leading sidepod curves. The air dams that tie into the chimneys are an interesting change but it's difficult to really see some of the surfaces due to the damn chrome paint.
The front wing span is shorter, which is interesting and the idea of the end plates seems to be to direct air inside the front wheel area, rather than around it. Most end plates have VGs aimed at the front tire to reduce drag ferom the front tires. McLaren still do that with the bottom of the end plate but other teams are creating multiple VGs along the end plate whereas McLaren doesn't APPEAR to be doing that. I say appearing because until you see the actual flows (Ron hasn't shared them with me yet

) uyou don't know for sure what's happening.
A friend with some inside knowledge told me that the aero focus is on drag these days so I guess down force is not a problem, like it was a few years ago. Still, I remember McLaren having to fight thru the seasons to increase front grip. It will be interesting to see if they have to do that again this year.