I don't know about the Tab S7 but I was coming from a Tab S6 and hated using it in comparison to a flagship phone because of the 60Hz screen and general sluggish feel of it (again, in comparison to flagship phones). I bought the Tab S6 about a couple months before the Tab S7 came out and right away it felt a couple generations behind the flagship phones that where out at the time (I think I was on the S20 Ultra) so I really wanted a tablet that felt more on par with a flagship phone so in my case, coming from a Tab S6 the S8 Ultra was definitely worth it. In fact, if not for the pre-order bundle deal with the Tab S8U/S22U I might of even skipped upgrading my phone this year but the with the combo deal it was a no brainer to upgrade even if I didn't really need the new phone.
One thing I think I remember about the Tab S7 is that the display didn't have as good of deep blacks as the Tab S6 or something to that effect, it's been a while since looking at Tab S7 reviews so I might not remembering correct there. But I would say that if there's not something specific that you're looking to get out of a new tablet like I was (wanting a 120Hz display instead of a 60Hz display, faster performing closer to that of flagship phones, and a larger screen for media consumption) it's probably not worth it. Research what you would like the Tab S7 to do better and see if the Tab S8 offers a better experience to what you're looking for. I completely couldn't deal with a 60Hz display anymore when my phone was 120Hz and my PC is 144Hz that 60Hz display just drove me nuts lol.