Do not leave anything on the coach overnight. Our cycling shoes were stolen from off the coach overnight just three days into the holiday and there was no sign of a break-in.
Be prepared for early starts. The hotels are much better than expected and all have internet (usually free).
If the weather is poor in Hanoi, consider not taking the trip to Halong Bay as the you spend over eight hours on a coach driving through uninteresting scenery and, if visibility is poor then the bay is a disappointment. As an alternative would recommend visiting HCM Mausoleum in the morning when you can get inside (you don't do this on the guided tour).
We added a further six days to the trip and flew down to the island of Phu Quoc for R&R. Finishing in Hanoi is a bit of a disappointment (weather poor and people not as welcoming) and everyone was jealous that we were going to get some sun. Would highly recommend the Beach Club (cheap and intimate) on Long Beach, Phu Quoc.
There was a discernable difference in attitude between the people of the south and the north. The further south you are the more friendly the people. That's not to say that Hanoi was unfriendly but just different to the south of Vietnam.
As a result, our thoughts are that the trip would be better if there were more days cycling and finished in Hue. Whilst the sleeper train to Hanoi is an experience and better than expected, Hanoi itself is not that spectacular and the last 3/4 days have no cycling at all, just sightseeing. Although that's clear from the itinerary, it's a bit of a let down.