I think it depends, for 2 reasons: 1) Each region of Brazil has their word for "cool" (as "legal" is the one more used at TV, is more popular in the country) ... but in regional levels, there are other words even more popular than "legal". For example "massa", "irado", "bacana", "da hora", "maneiro", "bala", "show", "sinistro", depending of the region. 2) With globalization, lately more and more people in Brazil are getting used with the words "Gira" and "Fixe" used in Portugal. So, in my opinion, if you use "Gira" in Brazil ... people will reacts the same way if a Brazilian that came of another region uses "Massa" for example.

Cool in european Portuguese it's "fixe" sometimes you can also use cool but isn't common. If you say someone it's giro (a) that mean she / he is good-looking, but you can say "Que giro!" as a exclamation.

To begin with, I've never heard "gira" in my entire life, but Brazil is huge and maybe in other regions it's common. Who knows... Spoking as a person who lives in the State of São Paulo, I would say that "cool" is "legal". But, there are some levels of "coolness", like "cool", "awesome", "sweet", "sick", "dope" and so on. The same goes for Brazilian Portuguese. We've got "da hora", "irado", "massa", "bacana", and so on. BUT, I don't think that you should sweat on all these words, trying to memorize them. Stick with one and try to change the intonation to express the correct "level of coolness". Most of the time I use "da hora". But depending on how "da hora" something is, I put some words together with that. Examples: Que da hora! Poco da hora! Véi, é muito da hora. BUT, again, I'm a 22 y.o. guy from Brazilian middle class. So, you'll have to consider whom you are talking to and what image do you want to project for yourself. After considering it all, my overall tip would be: stick with "legal". Intonation counts more than words to express your excitement about something. And, as the time goes by you'll acquiring more words for your "coolness" vocabulary. Hope it helps. =]

I recommend you use Legal (cool \ nice) in Brazil because everywhere understand. the other words are regional slangs.

Not say "Gira" in brasil only "Legal"