TBH, the answer is pretty much the same as it would be for any spreadsheet that is not Excel - while it will probably do 90% or even 99% of what Excel will do, the 1% to 10% that it
doesn't do is often a deal-breaker for a lot of people - particularly people who do more than just build simple spreadsheets with formulas.
In my case, for just one example, Excel does the following which, as far as I am aware, there is no equivalent in OpenOffice (note, while these are all different things, they are all the same theme - third parties have written extensions to Excel which don't work in other spreadsheets):
1) It interfaces directly with our company's ERP system for both pulling data for analytics and for making mass updates to data where needed (for example, we added a new field to track on customers - were able to open our customer list in Excel and update them directly without having to do an export->change->import process).
2) We are able to use
@risk to do monte-carlo simulation within Excel directly.
3) Our financial analysis, reporting, and budgeting tool (called Solver - this is different from the "Solver" tool that comes with Excel) runs within Excel. This is also part of our ERP (it's an external piece, but integrated directly within the ERP). Our managers are able to access a budgeting model where they enter their respective budgets throughout the year, and they are then able to pull down financials related to their departments in real time, all within Excel. Our senior executives are able to see the company financial performance against the overall budget via a web application, again, in real time.
Aside from third-party support, the other major difference with Excel is simply that Microsoft dumps a
huge amount of R&D into improving Excel, with quite a number of new features being introduced with every major version. Many of these features are the "holy crap, why didn't they come up with this before?" variety, and are now features that are in wide use today (and which I personally use very often). A few that come to mind that are fairly new (as in, came out in the past 5 or so years) include FlashFill, XLOOKUP, OData connectivity, PowerQuery, and tighter integrations into PowerBI. Some of these may exist in other spreadsheets, but many of them don't.
