Thanks Mark - A sensible answer at last.
I still don't like it though! Basically we're getting into something on completely unequal terms. Both parties need each other, but we're prepared to let the US to have more just because we're worried they might pull out. Well it strikes me that we need them just as much as they need us. I don't think it is usually justified in any negotiations to obtain something at any price.
I think that the principle objection should be that EU companies will not be able to control US companies. Whilst this might not matter to countries like Ireland or Portugal or wherever, it matters to the UK as we have a strong history of overseas investment. The whole thing stinks of grotesquely one-sided protectionism and I hope that our veto is deployed in the absence of a fair deal.
I do think most people would welcome the genuinely "open-skies' aspect of the deal.