I work remotely right now. We have 2-3 people call in and 4-5 people who are sitting together in person in a conference room in the office. The problem is that you lose the physical cues that indicate when it's someone's turn to talk. The remote workers end up trouncing all over everyone else when they try to speak, because they don't have the cues that the people in the conference room are using to determine it's someone's turn to talk. Remote people talk far less than they would otherwise because they can't tell when it's safe to interject. The meetings still function, but it's a significant disadvantage over being present in the same room. It can also be hard to appropriately distinguish speakers until you learn the voices of your colleagues really well.