I was leery about staying here in light of the comments. However, I checked into day at 11am for a 2 night stay and so far the experience has been good. Room (304) is clean, and larger than most European. Bed is firm, but not too hard. Deco is dated (1960s) but functional. At first the wifi did not work, but as soon as I reported it, they fixed it. They do charge for wifi, which I thought was free. However, I am able to pick up a Boingo connection at no charge on my laptop. Buying wifin through hotel is only $5 Euro for 12 hrs which is not a bad price. Bathroom is large but shower, like much of european showers is small. I look forward to the breakfast in the AM.
Given my awful experience in Catania, I did ask for a bug repellant machine. I dont know if it is needed, but that way I wont experience mosquitos like in Sicily.
The location of the Grand Hotel Duomo could not be any closer to the Duomo and leaning tower. Pictures that others have posted look like the hotel. Aesthetics/visual sez the hotel is not special, other than its location relative to the primary tourist attraction.

We stopped in Pisa for one night to see the tower. This hotel is a 5 minute walk to the leaning tower and 10 minutes walk from the shopping district. The room was well equipped, clean, good bathroom and reasonably priced for what we got. I rate the hotel based on the €90 we paid bed and breakfast for a double for a city centre location.

The location of the hotel is fantastic. 2 minutes walking from the "Miracle Square" and the Pisa Leaning Tower. We arrived with the car driving from Nice and the staff has been very helpful in helping us parking the car almost in front of the hotel door.

They showed us different rooms, and a "suite" at the last floor. The suite is kind of scary, too big and empty, very old furniture and did not look nice, apart from a great balcony/terrace overlooking the Duomo.

We settled for a more refurbished room. The bed was comfortable enough, but not great, and the rest of the room was OK.

It's not for sure a 4 star, but if you want a great location, it's an OK one.

This hotel is not definitely a 4 stars hotel, having this category only for the usual equipments (tv, hairdresser, safe box, refrigerator...). All of them, like the whole hotel, are at least 30 years old. The hotel maybe was a quite good 4 stars hotel in the 70s or even earlier, looking at the historical entrance. But now the world has changed a bit... Rooms are really terrible, scarcely clean and always looking sadly outdated. Bathroom is really poor and very old. Position is fantastic, but you can't pay, and not so a small price, only for the location close to the Duomo and the Pisa Tower. Breakfast is inadequate, with industrial food only and no table service. Expect noise from the street below almost all the night (noise protection very poor in the rooms, especially at the lower floors).