Good to hear, however the service is good in Samut Prakan either. The immigration building sucks however the staff is really efficient and less moody than CW, though they deal with a lot of foreigners every day (many people from Myanmar stay there). Things like TM30, TM7 and 90d reports usually take no longer than 1 hour.
Keeping a passport is a method which was widely used in many socialists countries (eg former Soviet Union). However I just happened to be asked for it only one time in HCM city last year. I said this wouldn't be possible as the purpose of my visit to Vietnam was to apply for a spouse visa for Thailand thus I would need it for the Thai consulate. They nodded and they returned my passport after taking a photocopy of it. So I just think it's a few alpha commies mind, I was never required to leave my passport anywhere in Vietnam.