We thoroughly enjoyed our stay at the Marriott Fallsview, the view was absolutely breathtaking. I have heard the Marriott view is almost as good as embassy suites (which is voted as the best view of both the falls). It was the first time we have stayed in Niagara falls in the winter time and the view looked like something out of Narnia. We stayed in the 9th floor.
The hotel rooms were clean and the washrooms were well maintained.
One advice would be to take your own water as the water in the rooms were priced at a whopping $6.95. Also try book through a groupon site as the rates tend to be way cheap than booking through Marriott or a website like hotels.com

Could not of asked for a better weekend, We arrived Friday night for a Romantic Christmas. Upgraded our room for $20 to a 18th Floor Junior Suite, HIGHLY RECOMMEND!! The view from the room was breathtaking we could of just sat and stared at it all day. We had breakfast buffet vouchers for both days, buffet was ok nothing spectacular. Ate in the inhouse restaurant using a voucher as well, Dinner was delicious and staff was incredibly friendly and willing to answer our tourist questions. We will be staying here again next year!

Amazing views of the falls at this hotel.

When I checked in, opened my window and had a perfect view of both falls (Canadian and US). The festival of lights was also very decorative.

Stayed in a jacussi room, the tub the room everything was fully clean.

Had dinner at the hotel restaurant, again nice views of the falls. If your making reservations for the restaurant ask to get a table close to the window and not in a booth or at the back as you won't be able to enjoy the magnificant views.

Breakfast buffet was amazing, lots of choices, hashbrowns, eggs, bacon, fresh granola, and best of all custom omlets.

The view from our room took my breathe away, we stayed for two nights & saw many different faces of the falls.
The room was clean, tidy & comfortable. There were three of us sharing & my only problem was that there wasn't enough surface area to put out our personal belongings....not much of a problem I know, but a little annoying when you're looking for somewhere to put your things.
The walkway from the hotel to the falls was closed off which meant quite a long winded walk each day; I think anybody with mobility issues should be wary as I suspect even with the walkway open it will still be quite a lengthy walk; downhill on the way but uphill coming back!
To summarise, if the walk doesn't bother you, choose this hotel, you won't be sorry when you see the view!