I had a coworker who was stuck in limbo for a couple months due to this crap. His wife was not allowed to work due to this issue, and he wasn't allowed to work while some bureaucratic thing was being resolved. They were not allowed to leave the US for their home country, either, so they just had to live on savings for this period.
Sometimes they suggest you don't pass through border control posts if your visa isn't 100% done yet.
While my H1B (later L1B) was processing, I was legally allowed to enter the US for business trips (Visa Waiver with ESTA), but the lawyers really recommended against it.
The border control people apparently can see the pending application and sometimes tend to be in the "I think you want to come here early and start working" mood. That way one might get denied entry which in turn has a negative effect on the currently processing visa.
I was in this situation as a j-2 visa holder. I could not leave the us for more than two weeks and i was not allowed to work for the first three months of my residence.
