Not useless, however.
Give the contents of wikipedia to our own civilization a century ago and watch the outstanding progress. A lot of theories wouldn't need to be tested, once the accuracy of wikipedia was determined. Things like penicilin wouldn't have to be discovered by accident. Several chemical reactions, which are named after their inventors, wouldn't need discovering.
Several open questions would be answered in an instant. Heck, give wikipedia to us a decade ago, we hadn't even discovered exoplanets. That would tell us that they are out there, and the outlines of basic techniques to find them.
Even things like the best reentry shape for a spaceship. Or chemical elements previously undiscovered.
WRT that particular entry, it is in fact, very abstract. But give it to a university, no matter the tech level, they will figure it out, given time. There's a lot of missing information indeed, but people are very good at filling in the blanks.
I'll give you another example: http://en.wikipedia.org/wiki/Laser . It is cryptic too, but remember that the laser, once conceived theoretically, didn't have a practical use. Now, we can't live without them. That entry lists the practical uses right there.
There are many, many more examples. My argument is that, while you cannot give wikipedia to someone and expect that a civilization will come out on the other end, the knowledge that is there is priceless. That would require work, but I bet any reasonable government would provide the necessary financing.
Oh, almost forgot, weaponry. It has several outlines for weapons. Heck, even the type of antenna best used for radar would be enough information to completely change the events of the World Wars.
Another thing I just remembered: http://en.wikipedia.org/wiki/Helicopter . Helicopters were attempted for decades with no success, it says right there in the history section. But someone came up with the idea of flexible rotors. There, my last phrase is enough to point a team to the solution, even if the details about materials, manufacturing methods and the calculations are missing. But I bet people can figure it out.