We spent a week in a sea view room at the Bahia Del Duque the first week of July.
Overall we had a great time, loved the hotel, the facilities and the location. Having visited Coste Adeje for the last 5 years, we feel this truly is the nicest area in Tenerife and feels a thousand miles away from the typical resorts associated with Tenerife (i.e. Playa).
The resort is on a vast scale, the grounds were beautiful, established and well kept and it meant it didn't feel cramped although the hotel was very busy when we were there - probably around 80% capacity. Liked the layout with the restaurants scattered throughout the resort gave it a Spanish villagey feel. As the hotel is built on a hillside, there are loads of steps from the main buildings down to the pool so probably not great for people with walking difficulties (although there are golf carts that will pick you up to take you to other areas of the hotel to avoid all the steps).
Had a great room, overlooking the pool towards the sea, although the rooms are a little on the small side - fine for the 2 of us, but definitely couldn't be described as spacious. In our opinion, the Sea View is worth paying for - some of the garden view rooms were behind other buildings and overlooking rooftops so wouldn't have great views.
We stayed half board and went to the buffet the first night. This was standard buffet fare, and to be honest we found it disappointing although we're not fans of buffets generally. The whole buffet restaurant was disorganised, empty bowls weren't replenished, queues for everything, so by the time you'd queued for one thing, the rest of your food was cold. They seemed very short staffed and it took an age for drinks to arrive and plates to be cleared from the table.
The same was true at the breakfast buffet, they seemed short staffed - we were in breakfast fairly early - around 8/8.30 and it wasn't busy, but we probably returned to our table to have to clear our own plates at least 3 or 4 days out of 7. Whilst not a big deal, it's not the service you would normally expect at a true 5* hotel.
For the remainder of our stay, we went to the other hotel restaurants for dinner each night which were much better variety and quality. We enjoyed the brasserie, the Spanish restaurant and Hacienda, didn't make it to the Trattoria which was standard Italian pizza/pasta. The hotel had a special HB offer whilst we were there that was really good value. The a la carte restaurants had a HB menu - roughly 5/6 dishes per course to choose from, as opposed to the full menu if staying BB which offered greater selection and variety. We felt we got the best out of each restaurant's HB menus in a week - in the absence of a special HB offer, I would definitely go BB so that the menu choice is not limited.
Overall, this is the best hotel we have stayed in in Tenerife and would definitely return again in future.