Had the old 4K version, and bought this new 4K version for another TV (exact same, with new remote now). Truly an excellent piece of gear. It's a shame the home screen isn't a little less cluttered and confusing for new users, however it is definitely better with the more recent software update.
So the biggest thing by far is that this thing will play basically anything you throw at it direct play for Plex/Kodi. The Plex app is a bit average sometimes dropping to transcoding when it doesn't need to, however if you use Kodi on it and connect to Plex with PlexKodiConnect it will never need to transcode. Legit this thing can play everything, up to and including 4K HEVC 10 bit HDR content. The wifi is good enough to easily stream ~50GB movie files as well, assuming your router is up to the task.
Highly recommend plugging it into the AC power via adapter as it means it's always on and ready to go, you'll want to do this when doing the initial setup as well to sort out the remote functions and assign the on/off key for the TV CEC functions to work.
The only downside is the internal storage is a bit small, and with a large library the artwork cache might fill up on it. It's a shame the interface doesn't allow for a little more customisation as it truly would be the absolute perfect media serving beast. However 95% of the time i'm sitting inside Kodi anyway. The new remote is great though, I bought some for not-so-tech savvy family members during prime sales and having the dedicated Netflix button makes life a LOT easier.
Inevitably, your smart TV is going to become unusable due to upgrades and manufacturers crippling the hardware/software over time. Meanwhile, my firestick 4k from ~2 years ago still working flawlessly (and even better than the day I got it due to a couple of UI upgrades). If only I could buy a large quality dumb TV now, because truly, you just don't need a smart TV with these.
Hope the review helps, if it does mash the button below. Thanks :)