Good, not great.
This is the largest JW Marriott in the world. Knowing this, I was expecting to be wowed by the hotel. I wasn't. 
The hotel and complex is large and aesthetically pleasing, but the rooms are seriously lacking. They're just normal hotel rooms. Even as a Marriott Platinum member, we couldn't get a suite or even a corner room. Heck, we couldn't even get a room on one of the top 3 floors. I was rather disappointed to see this. I ran into a friend in the exec lounge who is a gold member and had checked in an hour prior to me and he had been upgraded. Maybe the hotel should hold some of their nicer rooms for their platinum guests instead of giving them away to the first check-ins of the day. Honestly, the room was no different than any standard Marriott room I've stayed in. The bathroom tried to be swanky, but it didn't pull it off. 
The exec lounge was very nicely set-up, but the evening hors d'oeuvres didn't do anything for me. I tried a couple of their obviously heated from frozen appetizers and decided to go downstairs to their sports bar to get a decent snack. Maybe that's the point behind it, they serve subpar snacks in the lounge so that people go buy stuff from their other areas. The evening snacks were so bad that we skipped the morning breakfast. As a huge breakfast fan, it's very rare that I'll pass up on a free breakfast, but I just wasn't in the mood to be disappointed again. 
We called for a late check-out and were offered noon. That's barely a late check-out at all. They reluctantly offered 12:30 as a thank you for being platinum members. Again, it just rubbed me the wrong way. The service was hit or miss. The valet team was exceptional. I don't think the $32 charge for overnight valet is overpriced... it's actually $3 less than the Conrad. But, the Conrad beats this hotel in just about every area. Their rooms are spectacular. Their lounge is phenomenal, and their service is impeccable. As a HHonors gold member, I'm frequently upgraded at the Conrad but couldn't receive anything other than a standard room as a platinum member at the JW. 
Oh well, back to the Conrad for future visits.