The patch is official. You can also download it at the German Sims2 site (http://www.diesims2.de/pages.view_frontpage.asp) and there's also a German list of the things it is supposed to fix.
However I have one neighborhood that I use for testing and the game crashed while loading it.:smt120 So I recommend you back up everything you like if you think you need to install the patch.
It is possible though thats it is a specific problem with my game that behaved quite strange after installing Bon Voyage. I had really weired neiborhood issues where the Lots from the Nightlife City would end up on the Bon Voyage Island.