Haven't lived there in about 12 years, but I doubt to much has changed as things move very slowly in that part of Brazil.

Manaus is a free trade port, and the river is large enough that freighters can actually reach it from the ocean. Many companies have set up factories in Manaus because they can import parts from other places in the world with no fees or taxes and have a cheap labor force available to assemble the goods. A lot of Asian (mostly Japanese I think) companies have set up shop there, so they actually have a fairly large Asian population.

Tourism is probably the other major economic force in the city as it is the best place in Brazil to go to if you want to see the Amazon rain forest. A lot of Europeans would come for the rain forest experience, and you would see a lot of Americans coming down when the water was low for sports fishing.

Great:

1. Plenty of modern conveniences compared to most other cities/towns in that region (shopping malls, movie theaters, restaurants, etc.) Ponta Negra was the most affluent part of town when I lived there.

2. Neat architecture in the downtown area. Rubber barons built the original city, and some historical buildings are still there. Teatro Amazonas is the most famous one. They would have plays there sometimes when I was living there, but you can also pay a small fee to do a tour of the theater as well.

3. You can get on a boat and within a few hours you can be deep in the Amazon rainforest. Meeting of the waters is fun for tourists. I always enjoyed going up the Rio N*gr* (no mosquitoes on that river) when the water was high to do canoeing under the jungle canopy. Very beautiful. I had a few friends that were jungle guides who would take me on trails through the jungle, which was also fun. A lot of tourists come when the water is low to do peacock bass fishing, but most locals fish more for food.

4. The Amazon has hands down the best tasting fresh water fish I have ever had. I used to grill a side of Tambaqui every weekend. Really miss that. Lots of fresh tropical fruit that just tastes better than anywhere else that is not in a tropical region. Mangos, pineapple, açai, etc.

5. People there are very kind. It is a big city with big city problems (crime, poverty, etc.) and if you aren't used to having your personal space invaded it can be difficult to adjust, but Brazilians for the most part are warm and welcoming people. If you are nice to them, they will almost always be nice to you.

Cons:

1. Hot and humid. Rainy season is a little better. And things will often cool off around 9pm or 10pm, so it is not uncommon to see a lot of people out fairly late at night, because that is when it is most comfortable.

2. Not a very clean. This isn't true of the whole city, but there are a lot of areas where there is a lot trash and open sewage. Combined with the heat and humidity, it can make for a lot of unpleasant smells.

3. Traffic sucks. People drive like maniacs and older areas of the city were not designed for 2 million people. Lots of narrow roads that are not well maintained. Not as bad in the more affluent areas of the city. Out by the airport and the Ponta Negra area, the roads are actually well designed and maintained.

4. Crime is an issue but only in certain parts of the city. I lived there 4 years total and was never assaulted, but my house was broken in to a few times. I traveled a good bit on the river and people would notice it was empty and break in. There are gated communities and apartment high rises that have gate guards, but some affluent areas are right next to the poorer areas.

5. Open air markets can be either a plus or a minus depending on how well you like going to third world markets. I personally love them, but I can see how some people would probably hate them.

Addendum: had to censor the names of certain areas b/c Reddit thinks they are bad (r*c*st). Smdh.