I've been to Malta a few time recently, wouldn't say it was very busy but theres enough movements to keep you happy (*))
Always cruise ships & ferries and normally a few cargo ships, not to mention the ship repair berths. The harbour on the otherside of the city has the navy & normally a few rig boats. "Captain Morgan" harbour cruises from Sliema will take you around the lot.
Theres also another comercial harbour called Mar......xxx (cant spell it) that is quite busy and dont forgetting the ferries to Gozo.
Have a good time, look forward to seeing the pic's