Reviewing My Book

I've been rereading my book when I could at work but spent a lot of today reading it. I'm still finding corrections and things that need to be changed (like mentioning a particular forum when I'm not with them anymore, believe me, that was changed).

I printed up my book, 2 pages per sheet. And I have a notebook beside me, marking what section needs to be updated or fixed. That way, I can read in my recliner with my feet up.

Upon reviewing my book, I feel like it's missing something. I don't know what it is yet. I know it's missing something. That oomph or spark or something. and it really bugs me that I can't put my finger on it. Does it need more detail? Does it need more explanation? Does it answer any questions in the end? What does it need?

It would be nice if I knew a well published author with years and years of experience who could tell me these things. I suppose agents and editors would help with that too. However, before I approach an agent, I'd like to try polishing my book first. But that brings up another question, when is a book really ready to be shown to an agent?

I'd appreciate any thoughts and comments, advice on this, so feel free to post!