This is most probably the only place in Laos that divides opinion among travellers.
There are those who think VV is a tourist colony where they can practice “sports” that would be impossible or plainly forbidden in their countries: tubing  (means riding an inflated tube driven at high speed by a local dubious company speedboat until you are expulsed centrifugally in brown, very dirty waters, haha), or zipwiring (jumping Tarzan-wise into the void on a wire and fall in the river) to shallow waters under the influence of blue meth, or bikini contests under the surprised eyes of the locals. The rest of the day is spent sleeping in hangover, in preparation of the raving nights that would look sinful even on Mykonos. There is also caving, trekking, kayaking around, for those young in mind and age who do not wish to leave a very toxic falang *  footprint in this lovely scenery, or simply their life.
And there are those who see in VV a place to relax in what seems to have been a paradise for zen, in the middle of fantastic karstic rocks.
Sadly, I belong into my own category. I prefer calmness, but will not resist seeing what is happening on the other side. So here's how I go about it: first measure precisely if I can survive one or the other activity before, then not give a shit about what I just measured and just go for it... Although I know my limits: I will never participate in a bikini contest.
Anyhow, staying at what proved to be the lowest-standard hotel of the trip (The elephant crossing) pushed me even more into staying out late, and I must say what I saw was definitely shocking for Lao standards. Barely dissimulated prostitution, illegal in Laos, in massage parlours where young girls are waiting on the row holding teddy bears (!) and young people drunk or under the influence of bizarre substances having such a ball that would put them in jail in their own countries.
My only advice would be, if you prefer to be on the safe(r) and definitely quieter side keep to the downstream part of the city.
My best part of the trip will be undoubtedly the bike ride to the Blue Lagoon. And I mean the ride, not the place itself that has been screwed by tourism and where the picture “Do not smoke weed here” was taken… The scenery on the way was one of the best I have seen, resembling a lot the Halong bay in Vietnam, but without water. And the dinner at the French owned “Chez lotus” (unknown to Trip advisor, thank God, but just after the paying wooden bridge, your bridge to calmness and beauty actually) one of the fondest memories for myself, a soaking wet falang biker in urgent need of good food and a big, BIG Lao beer.

*foreigner in Lao, from the word French

The pictures

The postcards

The films