Errr, uhhh, where to start. First, these guys have done pretty poor science for a pretty long time. Which is sad, because if it was real, they would have some really cool stuff. Second, the AIAA reference clears up a lot of confusion I had about this announcement. The AIAA hosts an 'advanced propulsion' workshop once a year. By advanced, think... well... scifi. It's not to say that legit researchers don't turn up there, because they do, it's just to say that they're not all legit. The proceedings of this conference are in fact published. Consequently, getting peer-reviewed, and published in this particular conference doesn't infer you're entirely legit.
This leaves us with why I don't think their science is entirely legit. I'll ignore all the 'violations of Newton's 2nd law' arguments, since those have been done out the yin yang by people who enjoy Newton's laws way more than I do. (Real physicists use Lagrangians, and Hamiltonians, not Newtons' Laws). My reason for doubting them comes form extensive experience of investigating the field they work in.
Here's the thing. They used a force meter from Woodward of Woodward Effect fame. Woodward's another guy that I'd really like to be correct. He's a nice guy, and a good public speaker. Sadly, the effect he purports to observe hasn't been proven out to the satisfaction of the scientific community either. The detector that didn't prove his effect is the detector that the Eagleworks team chose to use. Simply put Woodward's force meter wasn't believable because it amounted to watching highly oscillatory wiggles. These wiggles were deemed not to have enough significance, and the whole thing went away.
Consequently, when Eagleworks went looking for a force meter, and chose Woodward's, that was a bad, bad sign. I haven't seen a reason published that the meter is now viable. It's a huge red flag to those of us who have worked in the field.
One final clarification. It's not NASA Eagleworks, it's Eagleworks, funded by a NASA NIAC, (new, innovative, and advanced concepts), grant.