Here are some impressions that have developed thus far... It's hard to know what applies to brazilians as a whole, to the region, or just to the people I've been with over the past 2 weeks, but for now, I'm gonna let my experience shape my impression of 'Brazilians' in general:
Brazilians are a very welcoming people. They are hosting the world right now, and they seem to really enjoy it, and want visitors to enjoy brazil.
They eat a lot of cheese. Cheese with every meal.
Their meat is quite good but, man, do they like their meat salty! Saaalty!
Light on veggies, other than onions.
Fruits are good.
Food is expensive. Dining out seems common (i.e. daily) and I can eat cheaper in Honolulu. How do they pay for living?
They eat often. It feels we just move from one meal to the next without a whole lot in between.
When do these people work? Is the World Cup just one big fat national holiday?
Beer is light and uninspired (lagers) -- no big surprise, standard for South American countries.
They love air conditioning. They are a windows-closed, air-on kinna people. (Average temp the past few weeks has been maybe... 75-80?)
While I feel much less a gringo here than other parts of South America, something still marks me as an obvious extrangeiro. Actually, more specifically, obviously American. I've looked around me, and Americans do have a way of sticking out like a sore thumb. For many, it's the shoes. Or the American flag cape. But also, I've noticed that generally, the in-shape, active-looking women are distinctly American. We work out.
If a Brazilian knows a part of the US, it's Florida. Most likely Miami. (This was also true in other parts of South America)
Sharks here eat people. "Danger of shark: Avoid sea bath."
Cell phone etiquette is different. Countless times I have looked around at an entire table at a bar or restaurant, and all but perhaps one or two people are fixated on their tiny screens... The one or two probably ran out of battery.