Pretty much wherever I go I get fast speeds since joining Verizon a few weeks ago and I love it!
However, there is one specific area in Topsham Maine (04086) up near the Topsham Fair Mall where the 4G/LTE signal is very good (2-3 bars) but all of our phones experience extremely slow Internet speeds (usually anything you try to do results in a timeout/failure).
I have attached an image where I have circled the approximate area where we very consistently all get data failures or very, very slow data. It is very rare to see thigns work at all there. Sometimes when I'm inside a building I will drop back to 3G and get semi-acceptable data speeds for a time (128KB, maybe).
I have not been able to successfully complete a speedtest.net test in that area.

Other than that one area, Verizon is a complete rockstar around here. I love it!!!! But I am in that one spot fairly frequently and would LOVE to have good service there, please!