Stayed here last Thursday -- had a prepaid room at the Reykjavik Grand hotel, across the street, but when we arrived at 3:15 (3PM checkin time), they were "overbooked and already full" (which was bull, because we saw folks in other lines get keys, but, whatever), but they told us they'd walk us to the Hilton and get us a "nicer" room.
Hilton gave us a nice room on the 4th floor with a water view. There is no wifi access in the rooms, but good free access in the lobby (we have no HH status). Parking is easy, location is good for that part of town (30 minute walk to the happening part of town), restaurant buffet breakfast was excellent.