Although shared office spaces is good if you lack the necessary working space, and it also develops office camaraderie, it also has its share of disadvantages.
There can be a lot of interruptions. If visitors or clients or even co-workers need to visit a partner, it can cause lack of concentration for the other. It would be worse if the matter that needs to be discussed is sensitve. If this is the case, the partner with guests must meet other people in a conference room or some other venue.
There can also be a lack of privacy for some. People who share office spaces must mind what they say or read or express as there are other eyes and ears around. For people who are sensitive to this, having a shared office space may not be a very good idea.
One might not be able to be himself or herself when in a shared office space. One cannot be noisy, or talk as loudly over the phone. One cannot do anything normally when one is alone. For people, having a shared open space may be quite stifling.