such as.
being face to face with your SO or kids 24/7 with little to no breaks. My SO happens to work from home fulltime as well but completely different field. This is a big one for us that dont have fairytale relationships.
Picking small stuff up on the way to and from work doesnt happen. they turn into inconvenient day trips. (energy drinks, coffee, smokes, etc)
Keeping focus, for me at least, is a lot more difficult for the easily distracted. Discipline is definitely a must, but again its not that easy for everyone.
The line between work/home is one big gray area. Among being tethered 10 steps from your office at all times your work assumes you are avail pretty much 24/7. On the other hand, everyone else in the world like friends and family, think you on vacation 24/7.
of course being able to spend so much time with my 1yr old and upcoming son outweighs all that, but i do miss working in the office.