I admit I am partial to Ipanema and Leblon. I am very happy with our digs in Leblon, and find the location perfect for us. Deciding on a neighbourhood is a personal decision and other factors weigh in heavily such as budget and of course everything changes if you have kids. Here are my impressions of neighbourhoods around Rio most commonly frequented by foreigners living abroad, hopefully they help!
My overall impression: Amazing views and convenient location.
Pro's: Close to the beach and all of the splendors of Ipanema and Copacabana. Easy to walk everywhere.
Con's: The same as any of the downside of living in Copacabana (target for pickpockets, prostitutes and beggars, etc.).
Barra da Tijuca
My overall impression: Nice, clean, new, far from the action.
Pro's: Close to the biggest beach in Rio and the most "North-American-Like" amenities in terms of shopping and stores. Reasonably priced beach living compared to Ipanema/Leblon, in fact you can live like a king compared to what you'd spend there... Brand new developments. Many houses with beautiful yards ideal for families.
Con's: As this area's popularity increases so do its crime rates. Feels like North America (how about the Brazilian cultural experience?). There is a very large swamp in Barra which makes it an area mosquitoes particularly like. Barra is in close proximity to many favelas. In fact, if you are commuting to Rio (which is a "con" in itself in my books as it's a loooong drive every day, and apparently the roads can wash out occasionally when there are storms) you will drive past favelas no matter which route you take. Another con - it's not as easy to walk everywhere there as it would be in other areas, you must drive.
My overall impression: Best for tourists...
Pro's: Close to the beautiful beach , SugarLoaf Mountain and many tourist attractions. You can walk everywhere. Close to the lagoa. Much more affordable than Ipanema/Leblon.
Con's: The proximity to favelas. Because there are so many tourists in the area, it is a target for pickpockets, prostitutes and beggars, etc.
My overall impression: Good if you want to live in a house.
Pro's: Close to Leblon and the lagoa, has a state of the art hospital, many services on the street & walk-able. Reasonably priced living compared to Ipanema/Leblon, in fact you can very reasonably rent a large house in this area (but then you will probably have to hire your own round-the-clock security). Con's: The community is almost surrounded by favelas, which, as my driver told me yesterday, makes it dangerous at night.
My overall impression: Close to all of the action!
Pro's: Beach. Shopping. Restaurants. Safe.
Con's: Still a few areas where you have to be careful, safety wise. It can also be loud.
My overall impression: Amazing views and tons of beautiful apartments.
Pro's: The views, great paths for walking/running/cycling. Central location = easy access everywhere. Tons of apartments - lots of selection.
Con's: Lots of traffic. You can't swim in the lake. Depending on which side of the Lagoa you are on it might be quite a walk to get to amenities, etc.
My overall impression: The place to be!
Pro's: Quieter yet beautiful beach, great shopping, the best restaurants, walk everywhere and feel safe.
Con's: It can be loud.