Having gone on a trip with them late in 2010, I was truly impressed. We worked in a village community, side by side with families there, building latrines. In fact, our labor contribution was almost superfluous - but the people were warm and generous and truly seemed to enjoy appreciate having us there, even if we were not the tireless workers that they were.
In addition to the work and the interactions with the people in the village, almost every day also had an educational or cultural component. We were given a tour of Managua; we visited a rural school and local clinic; we were given a lively lecture on the history of Nicaragua; live musicians had us up and dancing one night after dinner.
El Porvenir's work trips conclude with a recreational weekend. Although it was a little mentally jarring to go from a poor village to a nice hotel in Granada, I very much appreciated the opportunity it see a bit more of Nicaragua and to relax a little before returning home to work.
Finally, I can't say enough good things about El Porvenir's staff. Our group leader was tireless and his English was excellent. His partner didn't speak English as well but she also did a fantastic job (including, but not limited to, overseeing our simply yet very tasty meals). It was also very nice that El Porvenir has their own van and trucks so transportation was easy. I would unequivocally recommend El Porvenir to anyone considering a volunteer vacation.
I've personally experienced the results of this organization in...
seeing the eagerness with which the community worked to build new latrines, both for the immediately improvement in quality of life (especially for those families who had had no latrine at all) but also their hope for the future, for cleaner water which would be one of the eventual results of the new latrines.
Ways to make it better...
If I had to make changes to this organization, I would...
give a little more information/orientation in advance of the work project. As a first-time volunteer, I was surprised that there was not always enough for everybody to do. Had I known this going in, I might have felt less awkward about it.