The Ambassador hotel of Waikiki is one of those hotels to stay in if the budget is reallll tight and you don't plan on doing much there besides sleeping and showering. It's clean, decent and does the job with almost no frills and a relatively central location.
It's about a 10 minute walk to the beach 3-4 blocks away but the main commercial and shopping drag of Waikiki is just one block away.
Noise is a factor depending on the floor and direction your room is facing but this nook of Waikiki isn't too bad. It's tucked just off the main intersection enough to be doable.
More than a motel but far less than a resort this hotel also seems popular with military workers, younger travelers and those just simply trying to do Hawaii on a tight budget. It's not a hole but it's very, very basic. Honestly it's in need of updating but it's doable if you go in with clear expectation of what you're getting.
A concierge is in the lobby wedged in next to the front door, there's valet, laundry facilities and a coffee stand just outside the front door. A bus stop is also just in front and Dollar rent a car is a short walk away. Wifi is free in common areas, a pool is on property and a small kitchenettes are available depending on the type of room booked.
Most activities on Oahu will pick you up and there is a wonderful wide island to explore as well as Waikiki beach not too far away. I say stay, make the best of it, use your saved dollars for why you're really in Hawaii and I think you'll be just fine.