You basically get the calculator app with iOS 18. To be fair, iOS 18 doesn't really do much for most iPads anyways. 😛
I updated both our iPad 7 and 9 to 18 and so far I haven't noticed it being much worse than iPadOS 17. Well, 17 was already pretty bad on the iPad 7 to begin with.
Customizable desktop icon placement (like Android has had forever) is nice and so is the new Control Center. Finally, easy access to shut down without resorting to Shortcuts.