LG's Android UI started off as a bad copy of TouchWiz back in the Gingerbread days, but more recently it's evolved into its own thing. That thing is not always good, but it's not horrendous either. LG has just posted a video preview of the LG UX 4.0, which will probably be used on the G4, and you can suffer through it watch it below.

https://youtu.be/IXjlzW2P-jA

The video is mostly in Korean, but I'm going to go ahead and assume the floating text doesn't contain anything past the usual empty platitudes and marketing-speak you get in teaser videos. There are a ton of long pans across stock photos and some rehashing of older UI features. The supposedly new UX preview starts at about the 1 minute mark.

A few of the things shown off in the teaser don't seem new to me, like the camera options. I'm pretty sure the LG G3 already has most of that. There's a new Smart Bulletin UI that includes content from more apps, which would be a nice improvement. That feature was essentially useless on the G3. It will supposedly include an Expert Mode Camera, a new gallery, and "Smart Alert."

The overall look isn't much different, as far as I can tell. I imagine we'll get all the details when the G4 is announced later this month.