It's easily one of the best smartphones out right now, by far LG's best. It's a clear upgrade from the G4 but only if you're willing to deal with the added size. I've found that I can deal with it; the phone is huge but it's not clumsy. The second screen helps navigating around the phone tremendously and somewhat offsets the size issue. Fast charging is amazing with the included charger and by far my favorite feature; yesterday I charged my phone from 25% to 80% in about 20 minutes. This is yet another feature that has me scratching my head as to why LG left it out of the G4.. apparently the G4 has quick charge capability but they didn't include a quick charger with it like they did with the V10.
All in all, it's one of the best all around phones out there right now, if you can deal with the size. MHL compatible, removable battery/SD, fingerprint scanner, quick charge, excellent screen, fast processor, etc etc.. there's no phones that I know of that combine all these features in one package other than the V10.