I've been there just two weeks ago. I was not in the water there (except my toes), but the beach was clean, and even the water looks pretty good. Waves are very calm - against the rough waves I have noticed at Maho Beach. I wished I should stayed at the city beach in Phillipsburg.
But you can't do it very wrong. Just enter a water taxi at the pier, and 5 minutes later you are at Phillipsburg Beach and have a look onto the beach. Even if this beach is not your choice, you are not wasting a lot of time (you are also right there for shopping).