I went to Ibiza a few years ago during May. It was the beginning of the party season, so pretty low key. The beaches were gorgeous. The food was spanish, so in my opinion delicious. We stayed in Ibiza Town (just outside the main city). I think San Antonio has a reputation as being a bigger party town. We did not hire a car, but took taxis or walked where we needed to go. The old town was definitely worth exploring and found some cute restaurants/shops. We went to one club night, which was cool....but I have never been a huge clubber and I think now pushing 30, I would give it a miss. If clubbing is not your thing, plenty of chill bars you can hang out in if you want to have a few drinks.
I would recommend Ibiza only if you are looking for a beach holiday or a clubbing holiday. Otherwise, I think it's probably limited on the culture side of things.