I stayed here last year on a free night certificate and got zero Diamond benefits. I even had to email them to get the 1000 myway points - and by the time they replied, my claim with Hilton was already approved.
Granted they were charging a ridiculous (even for Iceland) US$1000 for the night I was there at the time of booking, I perhaps should be grateful that there was still standard award availability!
Breakfast was excellent, but everyone gets it anyway, and it had better be excellent if you're charging $1000.
The bathroom section was very large compared to the overall size of the room. Also, these awkward bits of wall (not sure if structurally necessary or just part of design) significantly reduced the space around which one could walk:


Will I stay again? As a non-US resident, I can't earn silly amounts of Hilton points for spending a few bucks on a credit card, so likely only if there is a good paid rate (which to me means the low 30000s of ISK), and it's cheaper than the Nordica Hilton or I really need the Canopy's location. Also I will probably try out the Curio first.