If you are to summarize the advantages, it is that we can access the satellites that those satellites offer, everywhere in the world at any time (assuming a satellite is currently in the position where you want to use it). The specific advantages are endless. Widespread communications, internet, imagery, etc. Outside of that, there are some specific advantages such as space exploration unhindered from our atmosphere and Earth observation from above.One disadvantage is that they're expensive. From design, to production, to launch, to commanding and maintenance, every piece is ridiculously expensive. This is becoming less of an issue with micro-satellites but with current technology, micro-satellites can't do what larger satellites can do and usually burn up in the atmosphere within years, months or even weeks. JAXA, a Japanese space agency has begun implementing a way to overcome some of these issues using ion thrusters. This technology, along with Space X's advancement in cheaper space transport, will most likely allow satellites to start getting cheaper and cheaper.I believe that the biggest disadvantage to us, is our reliance on satellite technology. Everything we do every day relies on it, even if indirectly. Cell phones, GPS, the power grid, food transportation and processing, farming, etc all relies so heavily on space satellites that if they were gone today, modern society as we know it would come to a hault. Although we still have our satellites now, that doesn't mean we always will. There is a lot of congestion in space. Not only is there not much room for satellites in the most preferred orbits, but space junk is becoming a huge problem. It's a problem to track and it's also impossible at this point to get rid of it. Little specs of dust and large chunks of satellites that have crashed into each other are orbiting at tens of thousands of miles per hour which is very dangerous to other satellites. Some say that two or more satellite collisions in LEO would make LEO unusable. Outside of damage from space junk and uncontrolled satellites, there are many other threats to our satellites. Solar flares, coronal mass ejections, directed energy attacks, EMPs, unintentional or intentional interference, etc. It's a very sensitive system with billions of dollars spent just on protecting it to make sure that one day it doesn't fall in a matter of a few years or a few days.Although that may seem like it's not much of a disadvantage right now, while that level of catastrophe hasn't yet happened, it's still a huge burden on the military, world governments, and financial system.