I bought a groupon for this tour on a recent trip to San Diego. Even paying full price would have made the trip worth it. We did the short tour (3.5hours) which was long enough. Our group consisted of my grandparents (in their 80s), my parents (in their 50s), my husband and I (in our 20s), it's hard to find activities to please everyone, but this tour fit the bill. We saw sea lions, a grey whale and a pod of 300 dolphins. Do not be intimidated by the size of the boat (it seats 150 i think), everyone had a seat with a view of the water.
A few tips:
Bring snacks and water (they do have them available for purchase but easier to bring your own)
Bring sunscreen (even on a cloudy day the CA sun can be brutal)
wear a jacket or bring a blanket(it gets chilly on the water)
bring motion sickness medicine- just in case!