Very trendy, clean place in a fantastic location. Quiet building. Just a couple blocks from the beach and a very easy walk to shopping and the Old Town. Plenty of food and cafes all around. Some of the wall decorations and wall paint were showing some wear but it wasn't a big problem. I was not impressed with the check in system-- you have to enter info and credit card information into an online system that I found to be very glitchy and hard to navigate (I am a tech savy person). I also didn't like having to give my cc info outside of AirBNB. Then you have to download an app to your smartphone to access the building and unit for the first time-- be sure to do this well in advance if you don't have great cellular data service when you travel. You also have to get the keys from inside the unit before you are able to park which is an issue as there is no street parking in this area. In reverse, to get out of the garage at check out you have to exit the garage with keys then figure out a way to bring them back up to the unit for check out. Very inconvenient. Also, I would imagine that this unit could be very hot in summer. The daily high was only mid/high 60's when we visited and the back bedroom, despite having two fans going, was very warm. Something to consider.
The provided baby crib and high chair were in excellent condition and set up for our arrival. Rental company was quick to respond to inquiries.
Donostia was very charming and the food was excellent. We loved our time in the city. There are three playgrounds near here (one in each direction) and the one along the promenade (next to carousel) is excellent if you have kiddos. The aquarium is also worth a visit with littles.