The 5 star NHTSA safety rating is the same as the 2016s, I think. The only noteworthy finding to improve on, safety-wise, is with the IIHS's "marginal" rating of the "small overlap front", driver's front side corner. Hyundai seems like they're just "anticipating" a better score here, based on preliminary data, as the IIHS has yet to make public any of their findings.
The current gen's small overlap front rating was a concern for me. However, reading the IIHS's report claims that "Measures from the dummy indicate that injuries to the left-lower leg would be possible in a crash of this severity. The risk of significant injury to other body regions is low." That they use the word, "possible" is interesting.
In this same "small overlap front" test, they qualify all "good" ratings (good is their top score) to "head/neck", "chest", "hip/thigh" and a marginal rating (one rating score below good) to the "lower leg/foot" category. It may be significant to note that despite stating that the head may be "vulnerable" in this type of crash, the IIHS still classified the head region as "good", their top score.
Long story short, it remains to be seen what the IIHS has actually rated the 2017 in "small overlap front" category. And what it may actually mean.