Not quite as secure as Singapore but still a great fun city with the usual precautions. Pat Pong is a fun market but the 'girlie bars' best avoided unless you know what you are in for and are in a group. If you want a good massage reasonably priced then the shuttle bus crew can direct you.
A very westernised city, being a small boat Azamara can berth almost in the center. Take the shuttle bus into the city, 10 minutes, and walk around. Cu Chi Tunnels, interesting day out, worth the excursion
Once again Azamara will get closer to Hanoi and in the process will sail through Halong Bay which is spectacular. Further exploration of the bay by local boat is a must, many opportunities to do this independantyly of the excursions and much cheaper. Hanoi is a long bus ride 3.5 hrs, we didn't bother, those that did said it was worth while.