I though it was good, but then i never read the previous book, and I never expect films to now be like the books anyway.
As for them finding a boat, it should have been too difficult to find a small motor boat and ride across. She already was told about the survivor centre in Vermont, and it was only 'listening to god' that she have faith that it actually existed....
I dont really think there were too many plot holes...it just that something are never explained, but theres a logical reason for explanation for it.
Edit: I think the trap was set up by the 'main' monster guy, showing that they were developing some kind of intelligence (possibly a link to the main point of the book that it was Neville himself who had become the monster to the new form of humanity)