If you want a rundown on why TPP is bad and why fast tracking it through Congress is bad then read: The Most Nefarious Part Of The TPP Proposal: Making Copyright Reform Impossible | Techdirt.
If you want more information on what’s wrong with TPP then look here: EFF: Trans-Pacific Partnership Agreement.
The TPP is being written completely in secret so fast tracking it through Congress will mean our representatives could be agreeing to things they have not had the chance to discuss and the people have not had the chance to consider. Wikileaks has pieces of this agreement if you want to double check the people telling you to question the people telling you it is good.
If you want to contribute your voice to those apposing Fast Track and the TPP: EFF can help you.