Having played Fortnite on both PS4 and Switch, I find the Switch version very lacking graphically, I don't think it's using the device capabilities atm, I do think it have the potential to become the better version after a few updates as I found that I prefer handheld gaming a lot more than tv gaming.
Nitpicking I know, but one of the first things I noticed was the balloon on the party bus didn't have any reflections. On the PS4 version you can see the sun reflecting off it. Don't think it's miles off, but yeah it's capable of being a lot more polished.