Took my wife to see it when it came out. Unusual that she staid up for the whole movie. As a mother of a Son who has an unlimited license she said on the way out "He is not doing that". Challenge Coins (pins) are great. He is also LTJG Navy so he has that for his mother to worry about.
I'm not sure much can be said about it being over dramatized. Some of the back stories could change to add more connection with the characters. Maybe explosions were less extreme? If you watch the footage, I'm not so sure it wasn't as dramatic (at least, when considering the destruction) as it appears.
I appreciated how they avoided the politics of the spill. The story was about the people, as it should have been.
Some of the Coast Guard folks in the movie were actual Coasties. There was even audio (interview on TV in the movie) that involved a guy I worked with (the interview was from the spill).
I spent the month after the accident at the National Incident Command, in DC. I was deployed to the Unified Area Command in Louisiana the following month. A week or two after I left, they stopped the leak.