Would I stay there again? Adam, that is a tough question. The water in the Hilton side is nice and you can do some nice snorkeling. They maintain a decent amount of coral and fish around. During our stay, we did a tour where they took us around the island and the water in the other side (i think the tour guide said this was in front of the St. Regis and Four Seasons) was so different and pretty amazing. In general, the water quality is comparable to the rest of the island, but you won't see the blue lagoon that you usually see in pictures of Bora Bora staying at the Hilton. However, the water level to snorkel and clarity at the Hilton was decent. If I were to return, I would stay at the St. Regis because of the blue lagoon. Also, I think it caters more to honeymooners and couples.
The pool was an 8/10. It was an infinity pool, it was clean, but was an medium size. It didn't have a swim up bar. The beach was nice and not too rough. The thing i really enjoyed was that they have sail boats and they will take you out complimentary for 30 minute rides.
Other comments: If you decide to stay at the Hilton, book your tours before you check-in. When we stayed at the Hilton in Moorea, we were allowed to book on our own and the prices using the concierge desk had minimal increases. However, the Hilton Bora Bora is a different story. Once you check-in, you have to use their concierge which will charge you 30 - 50% above the price of the tour if you would've booked directly through the operator. I usually don't mind the markup, but it was a bit excessive in my opinion.
Hope this helps.