The TPP was basically a global circle-jerk. Things the countries were already doing and money being allocated that was already going to be allocated for benefits. The net positive is being part of a global community , the negatives are being ostracized by the rest of the world.

Negative penalties related to failing to keep in check with your promises (which were already things we are going to do anyway mind) are being shamed by the world and taking a loss of face. The negative penalty of pulling out (at least the major one that's projected) is conceding to China the world's research into the development of technology in alternate energy sources and possibly giving them good contention to being world leader in that field in the future.

As far as I could tell leaving was only harmful to the country, but I'd love to hear someone else explain it a bit further if you have more intimate knowledge of the details.

To the question asked of the thread, I like that he's preventing a republican majority from managing to successfully do a thing. It's pretty impressive how big of a roadblock him actively trying to succeed is to the legislative process.