They were absolutley fine and I never experienced any hostility whatsoever. I never broached the subject of the Falkands war as it seemed a sensitive subject, but it was mentioned to me on one or two occasions and the attitude was 'They are yours'.
There was, historically, huge investment in Argentina from the UK years ago, and that manifests itself in very obvious buildings like railway stations that look just like the ones we have here.
The one surprising aspect I didn't expect, and I heard this from numerous people, was their regret about the Royal Navy being defeated in the first battle of the River Plate in 1816 or whenever it was after Spain had granted them independence. They thought the country would be a far less corrupt place if they had been part of the British Empire with due legal processes being introduced.
Those were the thoughts of the locals that were never more than friendly when they found out I was British, and I have to say it didn't feel like a poor country when I was there. When I mentioned it, that was their response.
There wasn't any negative I can think of while I was there.