What we were shown, she seemed like a different person. It would make sense, given she's an adult, and people change. Adult Aang was drastically different from child Aang and so on. So at least for me, the scenes we saw visually with her, portrayed her as a different person. The Toph we saw in Book 4, was like plucked straight from ATLA. I know people have made some pretty good argument as to why it makes sense. And I can't say I disagree. I just kind of found it a bit jarring, personally. It's a minor gripe though, as I did love Toph in these scenes. And I much prefer this kind of cameo, to the Iroh and Zuko ones (Zuko was really underused).
I guess my bigger fear, is that the writers cave in and make Toph super fan service with the series wrapping up. I guess some would love it.