Not sure what you mean by this exactly, but I work in banking with a lot of "financial professionals", and the general opinion is that Excel is not good because it screws with numbers, whether its scientific notation (Why? Its just as long as the original number), rounding of numbers (had that with a large list of account numbers just last week where half the account numbers lost the last 3 digits) and there is no easy way of saying "just treat these as entered".
Even setting fields to text doesn't stop Excel from fucking around and overriding them to be date formatted if it feels like the balance could be.
The main issue is that Excel comes with Office and you aren't allowed to install other software so it forces you to use it and get used to it. It really wouldn't take much to be better than Excel.
Both xlsx can be exported and imported. It is just harder
It's not the case that calc is lacking any features which excel has in a finance situation.
mac - if you need battery