I am an economist and no, it’s pretty much a wash. Some good things that we would have gotten anyway if we hadn’t quit TPP, some bad restrictions that will make our auto industry less competitive globally.
The ITC says that USMCA will add +0.35% to GDP. But that comes entirely from reduction in trade uncertainty, which the President himself caused. More importantly, his post-USMCA tariff/border threats towards Mexico suggest that uncertainty will continue, regardless.
Here is the estimated impact with and without a reduction in trade uncertainty factored in. Without it, the impact is slightly negative. 
So basically, according to the Administration's own numbers, the only net positive effect of Congress passing USMCA is to alleviate the chilling effect of trade uncertainty with Mexico that the President himself caused.
That's kind of impressive, in a twisted way.
This is, by the way, the exact same report the GOP is holding up as evidence of the agreement's benefits. So I'm not drawing on some hostile partisan study here.
I want to emphasize that, if the President had honored the agreement once it was signed, it might well have reduced the trade uncertainty he introduced. But he followed it up with more threats, which make it hard to believe passing USMCA will really settle things.
So there's reason to doubt those gains - i.e., undoing the damage - will end up being realized.
