VNAV is pretty much the same on all the planes I have flown. Sketchy. But I have not flown the 787 or the latest guppies. It's usually OK, but it's not absolute and there are plenty of times when it's more hassle than its worth.

Today I watched it meander back and forth in both pitch and power while it tried to decide what it wanted to get the job done. DRAG REQUIRED, then thrust added, etc over and over. We were below 18K so I used V/S to fix that. Last week it was clearly going to miss a crossing. I won't let it violate me. I use it, but I have little faith in it. And once we're within 50 miles, it can quickly become more of a distraction than a benefit.

You can create a pretty good power off descent with just a little cranial activity prior to initiating the descent. We did it for decades prior to VNAV.