We stayed at the Omni for 3 nights, primarily because it was the site of our friends' wedding and reception. We very much enjoyed the location - right on the Riverwalk, and the bridge behind the hotel allowed for easy navigation of the great bars and restaurants there. We also took advantage of the pool, which was lovely! We very much liked that it was salt water, too.
The service was great at the hotel, and everyone we encountered from bartenders to the bell hops to the front desk were very pleasant! When I requested that the suite the bride and groom rented for the weekend be ready a couple of hours earlier than regular check-in time, the hotel graciously accommodated and everything went very smoothly!
My only complaint about the hotel is the room we received. (It should be noted that we booked the Classic Deluxe Room with views of the city, courtyard, or pool.) We ended up in room 340, which didn't have a view of anything - just the hallway. The only windows we had were on the French doors to the room, which only opened to the hallway, making our room incredibly dark. When I asked if we could be moved to a room with windows, I was told their rooms don't really have them, so we stayed put. I wish I would have asked for an upgrade so we could have had a balcony and the opportunity to get more light in the room itself. The other odd thing about this particular room is that the door to the bathroom doesn't completely open due to the placement of the toilet.
Overall, if you are looking for a great, central location to experience everything the Riverwalk has to offer, definitely check out the Omni! However, make sure to ask what type of room you're receiving upon check-in, especially if you don't want to feel like you're staying in an interior cabin of a cruise ship.