I have stayed there a couple of times. The beach and pool are very nice and offer a nice opportunity for walks. The restaurants in the hotel are OK - nothing to get excited about. There are a number of places to eat that are in the general area and within walking district. The restaurant on top of the Hotel San Juan is a TexMex type spot that is pretty popular and has a great view. The airport is really close and you can certainly see and hear planes. However, I would definitely consider another visit.
I have been to the San Juan Stellaris. Its Ok. Good beach, nice bars. Restaurants OK, not great. I went to the San Juan Nacional Hotel to the Palm Restaurant one night. Better casino over there too. Service was kind of lacking at the San Juan Stellaris, almost like they didn't care if you were a guest. Rooms were nice, newly renovated. The new Renaissance opened over this winter and that's next door.
Lovely hotel sooo much nicer than stellaris in my opinion. Im not into high rise city view from my room. Also, Stellaris gets sun for about 2 hours then the buildings give shade. This is not an issue here. It is only 15 minutes away from SJ but a world away. Nice beach, pool area Hammocks on the beach. Didnt eat there tried local places.