NBME Score of 470 correlates with a three digit score of 216. ( See http://www.usmle-forums.com/general-...rrelation.html
A three digit score of 216 correlates with 88-90 two digit score ( See http://www.usmle-forums.com/general-...it-scores.html
So it depends on what's your aim.
If you are aiming at upper nineties score then you need to improve yourself. If an upper eighty or lower ninety score is OK for you then it's a descent score