I attended a week long conference in New Orleans and stayed at the J.W. Marriott. The hotel was going through quite a bit of construction in the lobby area. The check in area of the lobby is not overly large anyway and the additional loss of space due to construction made things very tight, especially during what was a very busy check in. So, until construction is finished, just be aware this area is very tight and can be a bit overrun at really busy times.
The staff was all courteous and lovely - to a fault. I was greeted, offered assistance, and just simply welcomed at every turn.
The rooms are pretty typical for a Marriott/J.W. Marriott property, although I found the bathrooms to be smaller than what I thought was normal (at least in the room I was in - 2006). I was staying on my own in a room, but if you were traveling with two or more people staying in the same room if they are all the same size, this would have been a bit of a challenge I think.
As to location, this was the perfect spot to stay to see New Orleans. As other reviewers have noted, it is right on a trolley stop, it's located just a couple of blocks from Bourbon street, and it's, of course, right on canal street so the "classic" New Orleans French Quarter experience is just a block or so away. If you're looking for shopping or other attractions the Saks store is just down the street and the Aquarium and other educational sites are also within walking distance. I was staying at the hotel for a conference so shuttle bus service was provided to and from the convention center by my conference...if not, it's about a $6 taxi ride (with tip)...each time you needed to go to/from the convention center.
My only complaints were the wireless network and room service food quality. It was spotty and often dropped off. However, the hotel didn't charge me for the network access so I do wonder if they were having some trouble with it at the time as I don't think it was included as a freebie with my registration - but it could have been. I ordered room service one night (burger and fries) and was not impressed. I ordered the burger with the whole grain sandwich bread which came as ordered. However, the burger was dry and over cooked based on my order of medium and no "toppings" such as tomato, lettuce, pickle, onion, etc were included. In hindsight, I didn't ask for them...but most places include those or at least offer them. The service was very pleasant, but my food was not good. I also had the breakfast buffet at Shula's (the only restaurant in the hotel) one morning and wasn't impressed.
I paid a conference rate for the hotel which was extremely modest compared to the published rack rate and what I've seen it go for. My value rating of four stars is based on what I paid (about $160/night plus tax) ...
New Orleans is not my personal first choice travel destination but this was a good hotel in a relatively convenient location.