I'm not using it anymore, I just tested it to see if I could propose it as a substitute. In my testing I tried both open and ms formats: I started with old excel files which didn't work well, so then I tried open format files that were build up from a clean slate state, with the data imported from CSV files. After that didn't perform satisfactory either, I turned to the internet. After searching for the major issue that I encountered (slow in a large sheet), I came to the conclusion that calc could not be a full substitute for excell, so I never proposed it and we're still using ms office to this day.

I'm just going to copypaste some other people's thoughts with which I agree, saving me a bit of time:

*"If you work at a large company for a while you'll encounter a class of user that Calc doesn't really address. They're like super-specialists. They often have a deep knowledge of Excel, but are otherwise completely computer illiterate. They also work with large datasets and specific models. Calc isn't a replacement for them. Not just on a feature level, but on an accessibility level.

Look for Excel resources. Classes, books, articles, howtos, everywhere. Do the same for Calc and you'll struggle a lot more. There is stuff there, but it just isn't nearly as professional and rich. There is no great way to transition Excel users to Calc users and have them still be as productive.

In the Linux world, when we get those style of work-loads we generally put aside Calc / Excel as a tool and begin looking at programming languages (e.g., Python, Matlab). I feel like this somewhat handicaps our ability to reach those users.

for basic use though, it's perfectly acceptable. I just wouldn't consider it a poweruser tool, and those power users are what make Office a multibillion dollar product for MS."*

*"Sadly, it's just not there in book.

The only time I try to use LOCALC is when I have a few hundreds/thousands of rows of formatted values to sort into a simple graph and performance is just abysmal.

I just tried again earlier this day and though most daily features are there for your regular user, all my "casual" uses of it ended up underlining the severe performance problems.

Maybe my uses are far more corner case than I believe..."*

https://old.reddit.com/r/linux/comments/9yjwyf/is_libreoffice_calc_truly_a_worthy_replacement/