* It's bound to SQLite, which imposes scalability challenges. It requires the webhead to be the one to execute the expensive queries. It can't parallelize beyond a single machine (or processor?).
* Contributors have trouble building it and messing with <code>LD_LIBRARY_PATH</code>.
* It cores on my development VM (but not for anybody else) when I pass it a bad regex, and I don't know why.
Here are some alternatives. Let's go shopping.