Here's a couple of common criticisms that will easily identify a commenter as having not read the agreement:
"the TPP (or ISDS) allows companies to sue countries for lost profits" (they don't)
"this is a power grab by pharmaceutical companies" (Pharma was second after Tobacco at being upset with the deal)
"it undermines Net Neutrality" (there are specific points allowing net neutrality regulation, NN was an Obama policy plank FFS)
"TPP worsens environmental or labor conditions" (it actually provides minimum standards that will improve these in developing countries specifically around overfishing, trade of endangered animals, and minimum wage. It's why the deal was endorsed by the WWF)
Then again maybe you did read it that way and still found it not that bad. I admit I didn't read it myself, but then again I'm from Europe so it's not my agreement to check. Still I have some faith in the EFF and other organisations which did read it and found it a dangerous agreement. And I really think it's a good thing that it's now harder to negotiate trade agreements in secret. It doesn't matter what the traditional way to negotiate these was, they have a big impact on the countries that implement them, and people deserve more than just a (representative) YES/NO to a huge number of potentially life-changing provisions at once.
https://www.reddit.com/r/IAmA/comments/453zzk/what_tpp_means...
It's also worth noting that they were invited to be part of the TPP negotiation process but declined. The agreement itself is not that difficult to read. It's meant to be used as a practical functional document, after all. The one thing that is a little tricky is that carveouts and exceptions to one mechanism or another may be listed in a separate chapter.
The EFF has an entire page on why the TPP was bad. The secrecy was only one part of it. https://www.eff.org/issues/tpp
Some HN headlines related to TPP:
"The Final Leaked TPP Text Is All That We Feared"
"TPP Text Confirms Massive Loss to Canadian Public Domain"
"UN Experts Say TPP and Fast Track Threaten Human Rights"
"TPP could thwart computer security research and tinkering"
I'm going to stop there because people can search the history for themselves. Hate on Trump all you want, but he did the right thing here.