I rarely use the search, but when I do I've never noticed it to not find what I know is there. Perhaps it is crap and there are many other hits its not returning for my searches - can you give an example of a bad search result you got?
It only does full-exact-word searches. If a word is written in a slightly different form or you write only a part of it, it won't find it.
Thanks. That's very poor alright, I'll keep a note of it.