Please understand that there is no Waikiki hotel that matches the consistency of most FS, RC, StR, and comparable 5 star luxury hotels. That being said, I think the Halekulani is unquestionably the finest luxury hotel on Waikiki.
We've stayed many times at the Halekulani, and generally it does have the best service and best dining of any hotel on Oahu. That said, it doesn't always get it right, which is why you see mixed reviews even for this hotel. We've had amazing stays...and one absolutle piss-poor stay marred by a ridiculously inept GM (who no longer is there btw). If we were to return to Oahu, the Halekulani likely would be our first choice...though being SPG Plat100, we'd also consider the Royal Hawaiian. But we'd expect the service standard at the Halekulani will be a bit higher on average.
It's a little bit like the Caribbean, another region famously plagued by poor service, often even at the top luxury hotels. Hawaii is better. But it still isn't as great as it could be.