I've never really used the voice functionality on my Sheild, mostly because I found it very limited for tasks besides opening apps and looking up movies. Also, for some reason it had frequent problems recognizing my voice. The new Google Assistant update really fixed and added so many features. One of my favorite features has to be the ability to open a specific show on an app using only my voice, for example when I want to watch The Office I just say "Open Netflix and play The Office" and it quickly resumes my last episode. It's so convenient and intuitive. They also kept the ability to talk to extensions such as Akinator, which I was pleasantly surprised to see and I had a lot of fun with it and others such as Trump Caster. Voice recognition also seemed to greatly improve in this update. Overall I'm really impressed with the functionality and integration Google/Nvidia was able to achieve with this update and it was definitely worth the wait imo.
Plex needs to step their game up. 98% of what I watch on the shield is my own library. I would kill to be able to say "Hey Google, turn on the shield and play Paw Patrol in Plex" to shut my kids up.