As usual the media has blown it way out of proportion.
An emergency Airworthiness Directive(AD) on the lithium ion batteries is the
only thing that grounded the airplane. The AD reads "prior to further flight modify the battery system." Boeing and the FAA will work out how that is to be done and the AD will be modified.
I'm not sure, but I would bet other country's aviation regulatory bodies have issued their versions of an emergency AD as well.
For those that do not know, AD's are a part(FAR 39 to be exact) of the FAR's(Federal Aviation Regulations) and are mandatory. If you do not comply with any AD, your airplane is unairworthy and not legal to fly. Period.
An emergency AD is pretty extreme and does not happen very often, and almost all of them will say "Prior to further flight, fix the ...." Normal AD's will have a certain length of time(flight hours, days, months) to fix the problem after the date they become effective.
I laugh everytime I've read "United(or insert other airline here) has
decided to comply with the FAA instructions", like they really have a choice! A private owner might be able to ignore an AD at his own risk, but a airline operator or charter operator will face certificate revocation and heavy fines if they tried to pull that.
The other issues-fuel leaks, window cracks, and the other things mentioned are probably just teething troubles of a new airplane design.