What are the choices?.

There's public transport (bus), a shuttle run by an airline, then there are Taxis:

http://www.tripadvisor.com/ShowTopic-g293921-i8432-k6606146-Public_transport_Noi_Bai_Airport_to_Hanoi_city_centre-Vietnam.html

http://www.hanoiairportonline.com/hanoi-airport-transportation/

Taxis, we can hire at the Airport. Also, if you are travelling to a hotel in downtown Hanoi, an airport pick-up can be pre-arranged with the Hotel. Some taxis can also be booked online. They are listed here:

http://www.tripadvisor.com/Travel-g293924-c127968/Hanoi:Vietnam:Airport.Transport.html

Any experiences using any of these routes.

Vietnam airlines shuttle bus is the best option if your going to hoan kiem.

Otherwise, search online for many pre-arranged transfer options.

Forget taxi's altogether, not an option foor foreigners arriving via air. They are not safe.

Here are some online sites for pre-arranged transfers from Noi Bai Hanoi Airport to downtown Hanoi:

1) TaxiAirport - 230,000 VND (Sharing cab with others), 300,000 VND (Private, non-metered)

2) AirportTaxi - 200,000 VND (Sharing), 350,000 VND (private, non-metered)

3) NoiBaiServices - 18 USD

4) NoiBaiTaxi - 15 USD

5) VietnamTransferService - 16 USD

6) hanoitransferservice - 16 USD

I booked through TaxiAirport. The company airporttaxi seems like their sister company. The driver will have your name badge and will meet you at the arrivals hall (this is actually near the entrance/exit to the airport). So before you actually exit airport and get in the cab, make it a point to exchange money or use ATM. If you turn right (before the exit) there is a Bank of Investment and Development of Vietnam (BIDV) Branch offers good rates. Rate received was 1 USD = 21,919 VND. probably worth ensuring that you have exact change to pay driver before leaving the bank.

Don't know if TaxiAirport driver would have accepted USD (or at what rate the conversion would have been done by driver), so, I changed USD to Dong before leaving airport to pay Taxi. It only took about 30 minutes to reach hotel, at around 10 pm. If your flight arrives in Hanoi at this time, it could work out for the best, although you don't have the shuttle option, you would pretty much cruise to your hotel with pre-arranged transfer option.

edit: there are reports that BIDV bank ATM's at Airport charge a 99,000 VND Fee.

I once made the mistake of insisting on the meter taxi price to the airport.

Actually came out a fair bit more than the fixed price quoted.

hanoi transfer service is good. i use multiple times both to and fro. never a problem. pay in advance with paypal.

never get your sim or data plan at the airport. theyll rip you every time and will only sell you the most expensive plan available and act like they dont speak english if you ask.