I stayed at the Mnar Castle for 6 weeks last October to November 2019. I thought it was lovely at first but after such a lengthy stay I observed some issues which would discourage me from staying there again.
First, the hotel is in the middle of nowhere. There is one single restaurant across a busy road and a dining room in the hotel. neither one serves alcohol. There IS a shuttle, but there are limitations to where it will take you, only to a couple of places and getting them to pick you up is a challenge, you must phone the hotel to make arrangements and often they are not very organized.
Secondly, the Hotel is crawling with young families. If you have three or four children yourself I guess you might appreciate that, but if you are a sophisticated couple or single you could be irritated by all the noisy families everywhere. The breakfast room, which serves a large buffet, (no sneeze glass, just buffet tables) is very nice but the young children touch all the food. Inevitably there will be screaming babies in there and some even ride scooters around the room, or race around the tables or lots of crying and shouting. If you are looking for a good nights sleep, be aware that a screaming baby might keep you up to the wee small hours.
Thirdly, No soundproofing in any of the rooms. I knew whenever any of my neighbors was using the toilet at 4 am and I knew precisely what they were doing. Yikes!
Fourthly, Do not ask the women at the front desk for suggestions on where to go in Tangier because they only know what is on the property. Horse riding, dune buggy riding and the odd bus tour. If you ask them about anything authentic they will send you to overpriced tourist spots. That's because they don't explore Tangier properly themselves. I had an episode with another Canadian couple on a trip to Chefchouen, the blue city. The girl at the desk booked us on a private car which was several times more expensive than the one we understood her to be booking us on. I paid the difference, but the other couple didn't pay and checked out early. The trip was a little spoiled for them. If you want info on what to see in Tangier, use the Internet and then ask the locals.
Fifthly. Do not under any circumstances bring valuables with you to this hotel. There are no room safes and not even a main safe where you can store passports, cash, camera equipment, jewelry or watches. I had a pair of Chanel earrings stolen by someone entering my suite, possible a chambermaid? when I was out. I did tell one of the front desk girls about it and she was horrified promising me if I could remember the day it happened, the maid would be promptly fired. But I didn't want anybody to be fired so I didn't say.
Sixthly. Although the main shuttle driver, who by the way spoke not a word of English or French, just Arabic was a pleasant and accommodating sort, the driver that filled in on his day off came on to me several times which I found disrespectful. I didn't say anything at the time because he had a wife and family to support but if you are a woman travelling alone, stay to the middle or back of the bus when he is driving.
On a more positive note, I found the young gentleman who looked after the horse riding program incredibly helpful when I had a problem with a Microsoft word program on my laptop. I cannot say anything else but thanks a million you saved the day for me.
The hotel is clean, beds are comfortable, maid service is thorough, grounds are pretty, but I believe it's better to stay near the center of the city where the action is and where you have choices. The lack of good English spoken at Mnar Castle also makes things a challenge.