The Argentinean model - who has been dating the blonde beauty since February - is impressed by his girlfriend because she is a "business woman" and "professional singer" and has gushed she has sold more books than `Harry Potter` author J.K. Rowling in Europe.
Speaking in a radio interview in his homeland, he added: "She is like a registered mark that sells everything with her name on it."
The hunk also spoke of how he instantly felt attracted to the busty former glamour model when they first met at Sir Elton John`s post-Oscars bash but had no idea how much attention their relationship would receive.
He said: "The great thing of all this is I was at the party and I thought, `I like this girl.` And I went and I didn`t know anything about her, didn`t even know her name.
"The party ended, we had two days in Los Angeles, then I went to London. She warned me that it was going to be chaos, but I couldn`t have anticipated how much."
The pair have been on a week-long trip to Buenos Aires, Argentina, together, and Katie was due to meet Leandro`s parents while they were there.
However, the get-together was cancelled at the last minute because the couple have to now fly back to London on 08.04.11 due to an unforeseen commitment.
But Leandro hopes to take mother-of-three Katie back to the South American country in the near future. He told Argentinean breakfast TV show `AM`: "We have to rush back to London again.
"It`s something that came up at the last minute. The idea now is that Katie gets to know Buenos Aires a little. She loves what she`s seen so far. She really likes everything."