Because it was a quick hack (about 2 mins of coding) there is a lot of things it does wrong. If you specify "no comments" on a post, it will still show comments links. If you tell it not to auto format the post, it still will. And if I post a private, friends only, or friends group post that you should not be allowed to read, it will show it to you anyway. These problems are not due to the livejournal protocol, or php-lj, but simply because I didn't bother to write the code to check for this kind of stuff yet.
Enjoy, and please let me know if you see any errors, problems, or security holes (other than the ones mentioned above).