I played with OpenCyc once. It was quite hard to use because you had to learn things like CycL and I couldn't get their natural language processing module to work.
The knowledge base was impressively huge but it also took a lot of work to learn because at the lower levels it was extremely abstract. A lot of the assertions in the KB were establishing very low level stuff that only made sense if you were really into abstract logic or philosophy.
They made bold claims on their website for what it could do, but I could never reproduce them. There was supposedly a more advanced version called ResearchCyc though, which I didn't have access to.
That was exactly my reaction to it: it seemed to require sooooo much background knowledge about the entire system to do anything. And because you were warned about issues with consistency it seemed you were warned about just fudging some things. That it was a quick way to an application that couldn't work. The learning curve seemed daunting.
The knowledge base was impressively huge but it also took a lot of work to learn because at the lower levels it was extremely abstract. A lot of the assertions in the KB were establishing very low level stuff that only made sense if you were really into abstract logic or philosophy.
They made bold claims on their website for what it could do, but I could never reproduce them. There was supposedly a more advanced version called ResearchCyc though, which I didn't have access to.