I found the Sorolla Museum to be over-rated. It would be of great interest to lover's of Sorolla's art, wishing to gain an insight into his life, and where he lived, but for me, I enjoyed the other art museums far more than this one.
I liked that you could take photos (no flash) in this museum, and that the entry fee was relatively cheap (3 Euro, or free after 2pm Saturday). The tranquil gardens and setting were great, and the staff very friendly and knowledgeable. Just don't put this place in #2 spot in your itinerary of Madrid.