Not to turn this into a tax forum, but one of the things I was surprised by is that they give a permanent pass to previously inverted companies to engage in the purported evil behavior going forward, e.g., the "hopscotch" maneuver whereby earnings in a foreign sub of a US corp are loaned to the new foreign parent.
If you are an arb or otherwise interested in a pending merger, you need to examine the conditions in the merger agreement. Generally these are keyed to whether a change in law would cause the transaction to be treated as a full inversion, i.e., the nominal foreign acquiror to be treated as a US corporation. Merely depriving the parties of the collateral benefits of the inversion, e.g., preventing hopscotching, would not usually provide an out.