As the other comment said, it's basically Libreoffice Calc, so try installing that on your laptop and see if you can get used to it.

My opinion: not as polished as Google Sheets, but good enough. However it's much better than the web version of excel.

Also, your experience will depend on the server your using to run it. Lots of people try to run Nextcloud on very weak hardware to save costs, and it does run well. But office in particular needs a bit more compute and memory to feel fast.