Well, like I said, I wouldn't go spend the weekend there or build a Summer home, nor would I call it "safe." But it's not entirely "dangerous" either, at least not for spending a few hours there. Film crews have been there taking images of the damage and all sorts of things. (It also can depend on where in the area you are.) And the area is still considered to be uninhabitable for possibly another 20,000 years but you can walk around there for a few hours unprotected and you'd be mostly fine.
That all aside, I think saying it's worse than LVoDH is a bit silly. For me, at least. I liked this better than the last one, it didn't have quite the comic relief-y moments or the bullshit from Justin Long. And the movie was Rated-R, that alone makes it better than the last one!
The movie had plenty of stupid moments, didn't really have interesting villains, but it entertained me for 90 minutes and I walked away happy. (Especially since I didn't see a wedding ring on Lucy meaning her and Doofus Dinkus didn't hook up as was hinted at at the end of the last movie.)
I'd go see another Die Hard movie, fuck it. I enjoy the heck out of them.