Jumpdrives are a cool feature. Before 4.86 I never dreamed something like that could be implemented, same with PoBs.
You could say that jumping out of battle is a tactic, fine. But rejoining the fight with a fully restocked ship, jumping out again near death and repeating the process again and again just gets annoying for the other side and it doesn't make any sense. If there are multiple jump ships, it really becomes frustrating.
The only way to kill a jumping BS is by heavy ganking, there is no other way to do it in 30 seconds.
Jumpdrives are also usable only on some battleships, those with largest cargo space. Battleships with smallest cargo space can't even use the jumpdrive without sacrificing armor, few turrets and even downgrading the shield or you must have someone to carry the fuel for you... while those with largest cargo space, such as Rheinland BS and few Carriers can combine it even with a CAU5-CAU6 and still jump without anyone's help.
Jumpdrives really need some tweaking, as now, on some caps they're OP and on most others they're useless.