You are DEFINITELY going to love the S9 over the S7. It's so much faster/smoother and with a better camera. You might miss a couple camera modes that are gone in the S9 (like VR shots), but you can make up for those with 3rd party apps if needed.
Where you might find some trouble adjusting is if you haven't gotten the update to Oreo (can't even remember if the S7 has it or not). Especially the notifications is something you might struggle to adjust to and there are some features that have been moved around or dialed down (like the amount of customization possible in the messaging app or support for S-Notes), but overall I think you would enjoy it much more.
You're also moving from the flat version to a curved one, so that will take some getting used to (and the new form factor will also get in the way of your muscle memory, but that's easily overcome).