Freebase is interesting. I have played with it since the beginning, and I spent a lot of time with it recently because I just wrote a chapter for my new book on Freebase.

Freebase compares a little with DBpedia in that users contribute data to both (for DBpedia this is indirect since Wikipedia metadata is automatically scraped).

For me, Freebase became easier to use when they started generating RDF for queries.