I see you've posted this in a job-related forum. Are you visiting Vietnam for only 3 months? My guess is that you'd require special paperwork to work there and considering we are at the end of December 2011, you may not have the required paperwork ready by the time you wish to leave.
Share my experience of Vietnam? No way, it's over 40 years old and best forgotten.
But, be that as it may, I've heard and seen some pretty good things about business and Americans trying to do business as long as it's on the up & up. We have quite a few folks in our area with ties to Vietnam and from them I've found out that the American $ and investment as well as ongoing relationships are very welcome with little or no hint of our past realtionship with the Vietnamese people.
I have no experiences related to Vietnam at all, but since I'm now working in Thailand I can discuss some general issues.
To begin, there really isn't enough detail in your opening request to work with. What kind of work would you like to do, probably quality related, given this forum? Do you speak Vietnamese? Presumably the planned visit is something of a vacation and to investigate options, or is that not the case?
The next issues, after how it would be conceivable for you to contribute to a Vietnamese company, relate to visa concerns. In the past the best way to work abroad is to be a specialist in some highly demanded field that a multi-national company is looking for, in which case they would pay you at foreign (first world) pay scale, cover relocation, arrange visa processing, cover those expenses, etc. Obviously that's all going to run way beyond using local resources, and the Vietnamese government isn't likely to open employment to any company that pays a small fee, so restrictions will result. My understanding is that former paradigm is becoming less common and now only applies to limited special cases. What I would say about Thailand likely wouldn't apply directly in Vietnam, but in spite of restrictions a company can make a case for any hiring in spite of the restrictions provided there isn't clearly an open local labor market and they'll pay significant expenses.
Language really could be a major sticking point, of course. Some MNC's would do a lot of business in their native language and English use is somewhat international for some purposes but manufacturing work in Vietnam (where most quality work would occur) is going to require speaking, reading, and writing Vietnamese.
There is a good expat forum that covers multiple countries that you could check out to ask the same questions: orientexpat.com (in case it's relevant note that I've no connection to that site, and they're not selling anything aside from also linking to related personals business that funds the discussion forum).
If you just want to live in Vietnam for some reason teaching English is another option; it's the one thing native English speakers can do that they clearly can do better than residents. Visa issues still apply but in most Asian countries there is a lot of developed supply and demand for the work.
Interesting this bumps back up after 5 1/2 years. I'm still in Thailand, in Bangkok, and don't have much more to add about Vietnam or expat employment in general, but I'll ramble on a little anyway.
Thailand has probably changed more than Vietnam in that time. There is now a military government in Thailand. Oddly there had been one not so long prior to back then too, with a democratically elected government alternating with military governments as the people keep making bad choices. Sound familiar, USA? The US military isn't going to overthrow Trump's regime but how it might work out if the people make an awful choice of leader might seem more familiar. No offense intended to conservatives; if you think Trump is doing great we see things differently, but that comes up, opinions on things varying.
Back to the point here, openness to expat (foreigner) work permissions can change based on lots of factors. Foreigners are less welcome here in Thailand now, in general. Per my understanding--not based on much, really--Vietnam is more stable in terms of consistent government form.
I couldn't speculate about the degree to which Vietnam is successfully educating local Vietnamese people to cover technical field positions, the one area for foreign employment I'd mentioned before. The last 5 years saw the same trend continue in Thailand as before; less foreigner employment is required. If technical demand in industries could expand faster than training, for example if an IT field expanded rapidly, then even additional education and training could fall behind, but it isn't working out like that here.
Thailand has a thriving ex-pat presence. I know a person who built a retirement home in a small village about an hour's drive from Bangkok, and there are some places that cater to retirees, especially which need care. Cost in Thailand vs. cost in US, is much lower in Thailand. I don't know if Vietnam has that type of business.
Thailand also has some good medical and dental tourism hospitals.
Right, all that. I'm not familiar with special care facilities but there must be such places.
I regularly go to some of the hospitals you are probably referring to (funny how diseases are different in the tropics, so health issues come up more). Bumrungrad is the main one, popular with Middle Eastern visitors. Vichayut and Siriraj are in between that and better local hospitals, the other places I go, but there are others more geared towards foreigners than those two. Cosmetic surgery as an industry is also big here, just not quite on the same level as South Korea, I don't think.
I had talked about work in Thailand somewhere else on here but retirement is a different thing. Thailand is open about that, related to issuing visas, and there are plenty of retired expats here. There are a lot of working professionals too, they just keep making the paperwork harder, cutting back the numbers by weeding out unqualified teachers (you need a degree now; that wasn't always the case). I've talked a little to people online that have worked in Vietnam as well but I don't really know how it all goes there.
This part is drifting way off topic but an expat told an interesting story about dying here, discussing the subject online while he was in the process of dying of fibrosis of the lungs. His financial status wasn't great so he was in a typical local hospital for that. For some that would seem nightmarish, like the kind of places in horror movies, but really it's just rougher looking, and not air conditioned, with some functional losses in being sanitary. I visited another monk's father dying in such a place when I was a monk here (long story, that part). In the US that particular medical condition will usually kill you too, unless you can arrange for a lung transplant in time.
Foreigners / expats here tend to push their interpretation of living in Thailand towards it either being a paradise of sorts or a bit hellish but to me it's just slightly different. Lower-end medical care is less effective, no doubt about that, but then it's not so functional to be underfunded and uninsured in the US either.