People of Vietnam are friendly.  However, their way of expressing their feelings takes a bit getting used to.  In addition, street vendors are NOT representative of the people in general.

ALWAYS bargain for everything, including hotel rooms and tours!  You can get ripped off very easily if you don't!  I did. Hahaha

Internet Cafe is readily available and cheap.

People are friendly but street vendors will often ask you to buy things from them before allowing you to take pictures of them.

Ha Long Bay is awesome!  And if you can sleep on the top deck of the boat.  Don't buy a package tour where sleeping on the boat is included, just take the $18 dollar for two day tour and then negotiate with the boat captain.  A good price is $5 (I paid $16 through a guesthouse - OUCH!)

Street vendors will surround you as soon as you walk off the bus to buy things from them - a very interesting experience.

People of Saigon and Hanoi have very different view towards Americans.  As to what those feelings are, well, I think it is best left for you to find out.