the "Millennium" is suffering from a problem with one of its Mermaid propulsion systems. These podded propulsion units have been plagued with problems for years and have cost Celebrity Cruises millions of dollars already. The company has sued the British manufacturer Rolls-Royce for US$ 300 million over this. There have been a total of a dozen incidents already on the four "Millennium"-class ships.
Once must realize, however, that this disaster is not the cruise line's fault, but the cruise line is a victim of this, as well.
There is no reason to worry about the ship's seaworthyness or general condition because of the current problem. The pod in question is still in use but cannot be used to its full capacity. Plus, the ship has a second fully independent Mermaid pod, as well.
I cannot offer you additional advice but I hope the above is helpful, anyway.