Tet question ... can you help?

Nope, it is not like a total shut down.
You will find it more difficult to get shopping/eating by locals done, prices are commonly doubling/tripling ... . The smaller the place, you are visiting, the bigger the effects.
Banks and other governmental organizations will be closed. You should carry enough money with you, Visa extensions ... during this time era unlikely.
Emergency services like police, hospitals will operate on a (Vietnamese) minimum level.
Your accommodation should be booked, as well as tickets, if you not have yet - you  likely have to change travel planes or have to be VERY flexible. from February 14th - 17th, you should stay wherever you are, keep a small supply on foods/drinks, unless you have local guidance, as this are the three most affected days.
In bigger Cities like Saigon, Hanoi ... Nha Trang life will be very much as "normal", at least along the tourist miles. Just expect higher prices for everything.

Thanks after receiving your message, we have booked travel & accomodation tonight so hopefully all sorted now.
Great information thanks.

I am a foreigner and spent my time during Tet in both Saigon and Hanoi before. I am currently living in Hanoi, Vietnam running a security business.

According to experience, my advise for travelers, stay out of Vietnam during Tet period.

During this period,
1. Crime rate is usually higher (usually petty crimes such as pick pocket, snatch theft etc.)
2. Vietnamese are good alcohol consumers. Thus, happy season like this, traveling on the roads is unsafe as drink driving and phone driving is not strictly controlled.
3. Prices of Everything is more expensive. Local vendors will take this opportunity to charge foreigners more than locals themselves. Prices are not high to the extend of not affordable, but the feeling of being ripped off & dishonesty is what I detest.
4. Key personnel are more corrupted. So if you are involved in traffic accident or lose your passport, you can expect to pay a hefty price.
5. There will be nothing much on the streets in big cities except some tourist places as most city folks will be back in hometown celebrating.

Unless absolutely necessary for business or transit, I would issue travel advisory to stay out unless you have pre-arrange someone to plan and bring you around. As a foreigner, I feel Security & Safety during this season will be of paramount importance. Especially if you are in my field of business.

Having said this, Vietnam is basically a peaceful country with warming folks if you meet the right people.

If you require more information, feel free to PM me.

Cheers!

I've booked the whole 30 seater bus to take my family 8 hours to Chau Doc during Tet. Evidently there is some sort of temple there that lots of Vietnamese pilgrimage to just for a prayer.

Saigon is great during Tet.  It looks like something out of the Twilight Zone, since so many people are away doing the family thing.  There's plenty of places open and it's as safe as any other time of the year, as long as you're on your toes and aware of your surroundings.

Travel would be a headache, because of the sheer number of fellow travellers you'd have to deal with.

@khanh44
Phuoc Dien temple - it's an official historic site of interest.

The market place in Chau Doc is a bit grim and grubby.

It's worth going to dinner at the Victoria hotel which sits on the junction of the Chau Doc river and the Tonle Bassac river. Sit outside and watch the boats zipping up and down. There is a nice little bar there too.

You can get a passenger boat from next to the hotel that will take you to Phnom Penh, Cambodia in about four and a half hours. IIRC the boats leave Chau Doc at around 7 AM and get you into PP in time for lunch. Just across the road from the boat terminal in PP is (or was when I was last there) an Irish bar called the Green Vespa that does a cracking all day Irish breakfast. The boats return from PP at around 12:30, so an overnight stop is indicated.

Better fill a container or two with gas/petrol; Nhu Lan Restaurant and Bakery (50 & 64-68 Ham Nghi, Quan 1)(GPS: 10.771010,106.703980) will be open for food sales - restaurant closed first and second days of holiday.

Don't visit a VNese home, without exploit invitation, on first or second day of holiday.

Stock up on Red Packets (Red gifting envelopes) for your favourite unmarried female friends.

Companies, using traditional calendars, pay one months salary (or 4 weeks) (13 x 4 = 52) or the 13th month for holiday pay - before the break.

Remember, if you are staying at a hotel for the holiday, seek out your room maid (not the relief one) and tip her early in your stay - you will get better treatment. Can't understand people who tip maids when they leave.

I did that boat trip with my daughters 3 years ago. Dam'd not a single live jacket. and the trip was over a massive lake for over 5 hours. They need to improve on safety big time those people who run those flyboats.
Regards Ron.