A random shot of my calculator 5000 miles from home while I enjoy a beer near the Pacific. We had been discussing how much water was on earth and what size of a ball it would make. I have no affiliation with the brewing company so apologies for the product placement.
Is it difficult to get used to RPN?
Not really, it's harder to get used to algebraic calculators again after being used to RPN than it is to get used to RPN
Go FORTH and learn....
You do have to remind yourself at the beginning that you're using RPN, but after a while it feels a bit like working sums out on paper.