I really wanted to like the new Google Transit feature but it is going to fail for me for virtually every trip to Manhattan that I will take. That's because the closest Metro-North station for me is Hawthorne, NY which Google Maps inexplicably places about a mile from its actual location.
You can even see the train platform from Google Map's own satellite view at the real location. Zoom in on the "New Town Taxi" marker below.
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That's a shame. I really wanted this to work for me. I'll report the problem to their newsgroup but I have no idea how long this will be like this.